Answer:
a is 15, b is 15, c is -15, and d is -15 also
Step-by-step explanation:
The 2 parallel lines that surround the number are called "absolute value signs" everything inside them has an outcome of a positive number and in this case the number is 15. Like I said the number(s) inside the absolute value signs have to have a outcome of a positive number, notice in c and d there is a negative sign outside the absolute value signs. Therefore you multiply the negative seperately so, 15(-1) is -15.
