Examples with solutions for Addition and Subtraction of Directed Numbers: Worded problems

Exercise #1

Daniel has $10. He wants to buy a pack of cookies for $20.

How much money will Daniel have left if he buys the cookies?

Step-by-Step Solution

To solve this problem, let's work through it step-by-step:

  • Step 1: Identify what Daniel has and what he wants to do.
  • Step 2: Use the subtraction operation to calculate the money left after the purchase.

Step 1: Daniel starts with $10 \$10 .
Step 2: He wants to buy cookies costing $20 \$20 .

Using the subtraction formula to find the remaining money:

Remaining Money=$10−$20\text{Remaining Money} = \$10 - \$20

This calculation yields:

$10−$20=−$10\$10 - \$20 = -\$10

This result means Daniel will have −$10-\$10 left, indicating he lacks $10 to make this purchase.

The correct solution to the problem is −10\boxed{-10}.

Answer

−10 -10

Exercise #2

Which number gives a result of 10 when it is subtracted from -2?

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Set up the equation based on the problem statement.
  • Step 2: Solve the equation step-by-step.
  • Step 3: Compare with the answer choices to select the correct option.

Now, let's work through each step:

Step 1: The problem gives us the equation −2−x=10-2 - x = 10.

Step 2: To isolate xx, we start by adding 22 to both sides of the equation: −2−x+2=10+2 -2 - x + 2 = 10 + 2 −x=12 -x = 12

Then, multiply both sides by −1-1 to solve for xx: x=−12×−1 x = -12 \times -1 x=−12 x = -12

Step 3: Therefore, when x=−12x = -12, it satisfies the condition that −2−(−12)=10-2 - (-12) = 10.

Therefore, the solution to the problem is x=8 x = 8 .

Answer

8 8

Exercise #3

Which number gives us 41 when we subtract 5 from it?

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Set up the equation based on the problem statement.
  • Step 2: Solve the equation algebraically for x x .
  • Step 3: Verify the solution using the context of the problem.

Now, let's work through each step:
Step 1: Based on the problem, we have the equation:
x−5=41 x - 5 = 41 Step 2: To solve for x x , add 5 to both sides of the equation to get:
x−5+5=41+5 x - 5 + 5 = 41 + 5
Which simplifies to:
x=46 x = 46 Step 3: To verify, substitute 46 back into the context of the problem:
Subtract 5 from 46, which gives us:
46−5=41 46 - 5 = 41
This confirms our solution is consistent with the problem statement.

Therefore, the solution to the problem is x=46 x = 46 .

Answer

46 46

Exercise #4

Which number results in -19 when you subtract -14 from it?

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Recognize the relevant formula and rewrite the equation.
  • Step 2: Perform the arithmetic calculations to find x x .

Now, let's work through each step:
Step 1: We rewrite the equation x−(−14)=−19 x - (-14) = -19 as x+14=−19 x + 14 = -19 .
Step 2: To solve for x x , we subtract 14 from both sides:
x+14−14=−19−14 x + 14 - 14 = -19 - 14
This simplifies to:
x=−19−14=−33 x = -19 - 14 = -33 .

Therefore, the solution to the problem is x=−33 x = -33 .

Answer

−33 -33

Exercise #5

Which number gives us 7 if we add -4 to it?

Video Solution

Step-by-Step Solution

To solve this problem, we begin by formulating it as an algebraic equation based on the information given. We are asked to find a number such that adding -4 to it yields 7. Mathematically, this can be expressed as:

x+(−4)=7 x + (-4) = 7

which simplifies to:

x−4=7 x - 4 = 7

We solve for x x by adding 4 to both sides of the equation to isolate the variable:

  • x−4+4=7+4 x - 4 + 4 = 7 + 4

This results in:

x=11 x = 11

Therefore, the number we are looking for is 11 11 .

Answer

11 11

Exercise #6

Which number gives us -24 when we add -3 to it?

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Set up the equation using the given information.
  • Step 2: Rearrange the equation to solve for x x .
  • Step 3: Calculate the value of x x .

Now, let's work through each step:

Step 1: We are given that adding −3 -3 to a number x x results in −24 -24 . This can be written as:
x+(−3)=−24 x + (-3) = -24 .

Step 2: To isolate x x , we add 3 to both sides of the equation, as −3 -3 is the term being added:
x+(−3)+3=−24+3 x + (-3) + 3 = -24 + 3 .

Step 3: Simplifying the equation gives us:
x=−24+3 x = -24 + 3 .
Perform the addition on the right-hand side:
x=−21 x = -21 .

Therefore, the solution to the problem is that the number is −21 -21 .

Answer

−21 -21

Exercise #7

What number results in -17 when -5 is added to it?

Video Solution

Step-by-Step Solution

To solve this problem, we need to follow these steps:

  • Step 1: Write down the equation representing the problem: x+(−5)=−17 x + (-5) = -17 .
  • Step 2: Isolate the variable x x by performing basic arithmetic operations.

Now, let's work through each step:

Step 1: The equation given by the problem is x+(−5)=−17 x + (-5) = -17 . This means we need to find a number x x that, when -5 is added, results in -17.

Step 2: To solve for x x , we need to isolate it. We can do this by adding 5 to both sides of the equation:

x+(−5)+5=−17+5 x + (-5) + 5 = -17 + 5

On the left side, adding 5 cancels out the -5, leaving us with:

x=−17+5 x = -17 + 5

Now, perform the arithmetic operation on the right-hand side:

−17+5=−12 -17 + 5 = -12

Therefore, the number we are looking for is x=−12 x = -12 .

Thus, the solution to the problem is −12-12.

Answer

−12 -12

Exercise #8

Find a number that if we subtract (-4) from it we get 7

Video Solution

Answer

3 3

Exercise #9

Which number added to 2 gives us 6-?

Video Solution

Answer

−8 -8