Question

Susan solved 200-91 and decided to add her answer to 91 to check her work explain why this strategy works

Answer 1

This strategy works because if you subtract one number from another the sum of the two numbers should be the that is being subtracted from. (In this case, it's 200)

Answer 2

Property of additive inverse

Explanation:

The additive inverse of a number a is -a as:

a + (-a) = 0 = (-a) + a

So, Susan tried to add the additive inverse of her subtrahend 91.

Let's see how it works:

(200-91) + 91 = 200 + (-91 + 91) (associative property of addition)

= 200 + 0 (additive inverse property)

= 200, the original number.

Hence, her check is correct.