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7th grade Solve equations with a bracket like 3(x + 4) = 21 worksheet

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Solve equations with a bracket like 3(x + 4) = 21

Grade 7 Math Worksheet

NameDate

Circle the best answer, or write your answer on the line.

  1. Bo flips to the fraction page and finds 3(x − 1/3) = 5. What is x?

  2. Noah meets a negative number outside the parentheses: -2(x + 5) = 8. What is x?

  3. Pia circles the tricky one on the worksheet: -3(x − 1) = 15. What is x?

  4. Tala solves 5(x + 3) = 40 the distribute-first way. Which equation comes from spreading the 5 over the parentheses?

    • 5x + 15 = 40
    • 5x + 3 = 40
    • x + 15 = 40
    • 5x − 15 = 40

  5. Zee solves 4(x − 2) = 20 the distribute-first way. Which equation comes from spreading the 4 over the parentheses?

    • 4x + 8 = 20
    • 4x − 2 = 20
    • 4x − 8 = 20
    • x − 8 = 20

  6. Ari spreads the -2 over the parentheses in -2(x + 6) = 14. Which equation comes from spreading it?

    • -2x + 12 = 14
    • -2x − 12 = 14
    • x − 12 = 14
    • -2x + 6 = 14

  7. Jun's study group has four answers for -4(x + 2) = 12. Which value of x makes it true?

    • -5
    • 20
    • -3
    • -1

  8. Kira's class buys 4 kites. Each kite costs the same, and each needs $2 of string too. The class spends $36 in all. How many dollars does one kite cost?

  9. Noah solves 3(x + 4) = 21 by dividing first: divide both sides by 3, then subtract 4 from both sides. Which arithmetic does the same steps in the same order?

    • (21 − 4) ÷ 3
    • (21 ÷ 3) + 4
    • 21 ÷ 3
    • (21 ÷ 3) − 4

  10. Ren solves -4(x + 3) = 20 by dividing first: divide both sides by -4, then subtract 3 from both sides. Which arithmetic does the same steps in the same order?

    • (20 − 3) ÷ (-4)
    • 20 ÷ (-4)
    • (20 ÷ (-4)) + 3
    • (20 ÷ (-4)) − 3
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7th grade Solve equations with a bracket like 3(x + 4) = 21 worksheet – printable
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About this worksheet

Solve equations with a bracket like 3(x + 4) = 21. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can solve an equation like 3(x + 4) = 21 by dividing first: 21 ÷ 3 = 7, then 7 − 4 = 3.
  • I can solve it by spreading first: 3(x + 4) = 3x + 12, then 3x = 9, then x = 3, and see that both ways agree.
  • I can do it with negatives, decimals and fractions, like -2(x + 5) = 8 or (3/4)(x + 8) = 21, and check an answer by putting it back in.

Standard: 7.EE.B.4a

Words to know

parentheses: Parentheses around an expression. In 3(x + 4) the parentheses holds x + 4.

distribute (spread): Multiply the number outside by every term inside the parentheses.

divide first: Split the total by the number outside the parentheses, then deal with what is inside.

coefficient: The number multiplying x, or multiplying a whole parentheses.

bar model (tape diagram): Two bars of equal value: the left side on top, the right side below.

check: Put your answer back into the equation and see that both sides match.

Common mistakes

Your child took the extra number inside the parentheses off the total once, but the number outside the parentheses multiplies it too. Draw 3 pieces that are each x + 4 and count how many 4s there are.

Your child added the extra number in the parentheses when it had to come off, or took it off when it had to go back on.

Your child divided by the number outside the parentheses and stopped, so the answer is still x plus the extra number.

What to say

Ask: to get x alone, does this number come off or go back on?

Ask: that is what one whole piece is worth; how much of it is x?

Questions parents ask

What is the most common mistake with solve equations with a bracket like 3(x + 4) = 21?

Your child took the extra number inside the parentheses off the total once, but the number outside the parentheses multiplies it too. Draw 3 pieces that are each x + 4 and count how many 4s there are.

Are these 7th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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