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Chapter 6 · Equations · page 29 of 68

Two-step equations

levelGrade 7
standard7.EE.B.4
practiceTwo-step equations

An equation of the form ax + b = c or x/a + b = c. Two operations have been done to x, so two undo steps get it back.

How to use it

  1. Add or subtract to move the constant off the side with x.
  2. Multiply or divide to clear the coefficient.
  3. Substitute your answer back in to check.

Example

4x−6=22  ⇒  4x=28  ⇒  x=74x - 6 = 22 \;\Rightarrow\; 4x = 28 \;\Rightarrow\; x = 7
x3+2=5  ⇒  x3=3  ⇒  x=9\frac{x}{3} + 2 = 5 \;\Rightarrow\; \frac{x}{3} = 3 \;\Rightarrow\; x = 9

Where it goes wrong

  • Finding x/3 and stopping. You found a third of x, not x.
  • Adding 6 to one side and subtracting it from the other.

Related

Undo in reverse orderWhen the x term is negativeCheck by substitution
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