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

9-9.

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

If 3*x* = 18, then each *x* must be equal to 6.

Why does this make sense?

Would any other number work?

6

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