Solve Linear Equation: 12y+3y-10+7(y-4)=2y Step-by-Step

Linear Equations with Distributive Property

12y+3y10+7(y4)=2y 12y+3y-10+7(y-4)=2y

y=? y=?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solution
00:04 Open parentheses properly and multiply by each factor
00:18 Collect terms
00:23 We want to isolate the unknown Y
00:31 We'll arrange the equation so that Y is alone on one side
00:45 Isolate the unknown Y
00:57 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

12y+3y10+7(y4)=2y 12y+3y-10+7(y-4)=2y

y=? y=?

2

Step-by-step solution

To solve the equation 12y+3y10+7(y4)=2y12y + 3y - 10 + 7(y - 4) = 2y, follow these detailed steps:

  • Step 1: Apply the distributive property to 7(y4)7(y - 4).

This results in:
12y+3y10+7y28=2y12y + 3y - 10 + 7y - 28 = 2y.

  • Step 2: Combine like terms on the left side of the equation.

Combining terms, we have:
(12y+3y+7y)1028=2y(12y + 3y + 7y) - 10 - 28 = 2y
22y38=2y22y - 38 = 2y.

  • Step 3: Move all terms involving yy to one side of the equation and constant terms to the other side.

Subtract 2y2y from both sides:
22y2y=3822y - 2y = 38
20y=3820y = 38.

  • Step 4: Solve for yy by dividing both sides by 20.

y=3820=1.9y = \frac{38}{20} = 1.9.

Therefore, the solution to the equation is y=1.9 y = 1.9 .

3

Final Answer

1.9 1.9

Key Points to Remember

Essential concepts to master this topic
  • Distributive Property: Multiply term outside parentheses by every term inside
  • Technique: Combine like terms: 12y + 3y + 7y = 22y
  • Check: Substitute y = 1.9: 22(1.9) - 38 = 2(1.9) gives 3.8 = 3.8 ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting to distribute to all terms in parentheses
    Don't just multiply 7 × y = 7y and ignore the -4 inside parentheses = missing -28! This gives you 22y - 10 = 2y instead of 22y - 38 = 2y, leading to the wrong answer y = -0.5. Always distribute to every term inside parentheses: 7(y - 4) = 7y - 28.

Practice Quiz

Test your knowledge with interactive questions

Solve for X:

\( 3x=18 \)

FAQ

Everything you need to know about this question

Why do I need to distribute 7 to both y and -4?

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The distributive property says you must multiply the outside number by every term inside the parentheses. So 7(y4)=7×y+7×(4)=7y28 7(y - 4) = 7 \times y + 7 \times (-4) = 7y - 28 .

How do I combine like terms correctly?

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Look for terms with the same variable and power. Here, combine all the y terms: 12y+3y+7y=22y 12y + 3y + 7y = 22y , and combine constants: 10+(28)=38 -10 + (-28) = -38 .

What if I get a decimal answer like 1.9?

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Decimal answers are perfectly valid! You can also write it as a fraction: y=3820=1910=1.9 y = \frac{38}{20} = \frac{19}{10} = 1.9 . Both forms are correct.

How do I move terms to isolate y?

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Use inverse operations. To move 2y 2y from the right side, subtract it from both sides: 22y2y=38 22y - 2y = 38 . This gives you 20y=38 20y = 38 .

Why do I divide by 20 at the end?

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To isolate y, you need to undo the multiplication by 20. Since 20y=38 20y = 38 , divide both sides by 20: y=3820=1.9 y = \frac{38}{20} = 1.9 .

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