### Home > ACC7 > Chapter 2 Unit 1 > Lesson CC3: 2.1.7 > Problem2-68

2-68.

Read the Math Notes boxes in this lesson and for Lesson 2.1.5. Then examine the work below that shows one way to simplify the expression $3x+8+(x+10)$. Decide which property was used for each step.

 Expression What property was used? $3x+8+(x+10)$ Original expression $(3x+8+x)+10$ a. $(3x+x+8)+10$ b. $(4x+8)+10$ Added like terms $4x+(8+10)$ c. $4x+18$ Added like terms

What is the property used to rearrange parentheses with addition?

In part (b), some terms are moved. Why is this a legal move?

The answers are filled in below.

 Expression What property was used? $3x+8+(x+10)$ Original expression $(3x+8+x)+10$ (a). Associative Property of Addition $(3x+x+8)+10$ (b). Commutative Property $(4x+8)+10$ Added like terms $4x+(8+10)$ (c). Associative Property of Addition $4x+18$ Added like terms