You just need to substitute the values into the expression.
I always say hug it when you plug it...which means put ( )s around the number you are substituting into the expression.
-2ab² - 2b³
-2(-2)(-3)² - 2(-3)³
-2(-2)(9) - 2(-27)
4(9) - 2(-27)
36 + 54
90
The answer is a. 90
