use the associative law of addition to write an equivalent expression for

(m+np)+r

Study this site. Then tell us what you think you should write.

http://www.mathsisfun.com/associative-commutative-distributive.html

The associative law of addition states that changing the grouping of numbers being added does not change the sum. In other words, you can group the numbers differently without altering the final result.

To write an equivalent expression for (m+np)+r using the associative law of addition, we can change the grouping of the terms. To do this, we can group m with r and np together.

So, we can rewrite the expression as follows:

m + (np + r)

By doing this, we have changed the grouping of the terms but the sum remains the same.