Examples with solutions for Addition, Subtraction, Multiplication and Division: Using variables

Exercise #1

Solve the equation and find Y:

20×y+8×27=14 20\times y+8\times2-7=14

Video Solution

Step-by-Step Solution

We begin by placing parentheses around the two multiplication exercises:

(20×y)+(8×2)7=14 (20\times y)+(8\times2)-7=14

We then solve the exercises within the parentheses:

20y+167=14 20y+16-7=14

We simplify:

20y+9=14 20y+9=14

We move the sections:

20y=149 20y=14-9

20y=5 20y=5

We divide by 20:

y=520 y=\frac{5}{20}

y=55×4 y=\frac{5}{5\times4}

We simplify:

y=14 y=\frac{1}{4}

Answer

14 \frac{1}{4}

Exercise #2

2y1yy+4=8y 2y\cdot\frac{1}{y}-y+4=8y

y=? y=\text{?}

Video Solution

Step-by-Step Solution

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

  • Simplify the term 2y1y 2y \cdot \frac{1}{y}
  • Rearrange the equation to group similar terms
  • Solve for y y

Now, let's work through each step:

Step 1: Simplify the expression 2y1y 2y \cdot \frac{1}{y} .

The term 2y1y 2y \cdot \frac{1}{y} simplifies directly to 2 2 since y y in the numerator and denominator cancel each other out assuming y0 y \neq 0 . Therefore, the equation becomes:

2y+4=8y 2 - y + 4 = 8y

Step 2: Combine like terms on the left-hand side:

2+4=6 2 + 4 = 6 , so the equation now is 6y=8y 6 - y = 8y .

Step 3: Rearrange the equation to isolate y y on one side. Add y y to both sides to get rid of the negative y y :

6=8y+y 6 = 8y + y

This simplifies to:

6=9y 6 = 9y

Step 4: Solve for y y by dividing both sides by 9:

y=69 y = \frac{6}{9}

Simplify the fraction to get:

y=23 y = \frac{2}{3}

Therefore, the solution to the problem is 23 \frac{2}{3} .

Answer

23 \frac{2}{3}

Exercise #3

How much is x equal to?

2542 ⁣:x+18×2 ⁣:4=23 -25-42\colon x+18\times2\colon4=-23

Video Solution

Step-by-Step Solution

We begin by placing the multiplication exercise inside of parentheses:

2542 ⁣:x+(18×2) ⁣:4=23 -25-42\colon x+(18\times2)\colon4=-23

2542 ⁣:x+36 ⁣:4=23 -25-42\colon x+36\colon4=-23

We will then place the division exercise inside of parentheses:

2542 ⁣:x+(36 ⁣:4)=23 -25-42\colon x+(36\colon4)=-23

2542 ⁣:x+9=23 -25-42\colon x+9=-23

Next we rearrange the exercise in order to simplify it:

25+942 ⁣:x=23 -25+9-42\colon x=-23

(25+9)42 ⁣:x=23 (-25+9)-42\colon x=-23

We then solve the exercise inside of the parenthesis and obtain the following:

1642 ⁣:x=23 -16-42\colon x=-23

We rearrange the fractions and obtain the following:

42 ⁣:x=23+16 -42\colon x=-23+16

42 ⁣:x=7 -42\colon x=-7

We multiply by x and obtain the following:

42=7x -42=-7x

Lastly we divide by negative 7:

x=427=6 x=\frac{-42}{-7}=6

Answer

6