### Home > MC1 > Chapter 9 > Lesson 9.1.1 > Problem9-9

9-9.

Find the value of the variable that makes each equation true.

1. $3x + 2 = 20$

If $3x + 2 = 20$, then $3x$ must be equal to $18$. Why?

If $3x = 18$, then each $x$ must be equal to $6$.
Why does this make sense?
Would any other number work?

$6$

2. $2x - 1 = 23$

You can use reasoning similar to that for part (a).