CPM Homework Help : CAAC Problem 9-47

Mr. Guo is thinking of a number. When he takes the absolute value of his number, he gets $15$ . What could his number be? Is there more than one possible answer?

Hint:

Remember that the absolute value of a number is its distance from zero on the number line and it is always positive.
Can more than one number have the same absolute value? How is that possible?

Answer:

Either $15$ or $−15$ . Make sure you understand why.