### Home > MC2 > Chapter 7 > Lesson 7.1.2 > Problem 7-20

7-20.

*x* = 5.75

*x* = 5.2

Be sure to know how to get this answer using mental math. Recognize that 3.25 + 7.15 equals an even decimal, 10.4.

8(2) = 16

What must x be?

7-20.

*x* = 5.75

*x* = 5.2

Be sure to know how to get this answer using mental math. Recognize that 3.25 + 7.15 equals an even decimal, 10.4.

8(2) = 16

What must x be?