MOSTMATHSkill 08 · 6.EE.B.7, 7.EE.B.4

One- and two-step equations

An equation stays true as long as you do the same thing to both sides. To solve, undo the operations around the variable in reverse order: undo addition or subtraction first, then undo multiplication or division. Check by substituting your answer back in.

Example · Solve for k.

3k−1=23k - 1 = 2
Steps
  1. Undo the subtraction first: add 1 on both sides. Why first: the expression was built by multiplying then subtracting, so you undo it in reverse order.3k=2+1=3\displaystyle 3k = 2 + 1 = 3
  2. Undo the multiplication: divide both sides by 3.k=33=1\displaystyle k = \frac{3}{3} = 1
  3. Check by substituting back in.3⋅1−1=2\displaystyle 3 \cdot 1 - 1 = 2

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