Find the volume of the figure below for A, B, C

I’m stuck on this i don’t understand.

What is the effect on the graph of the parent function f(x) = x when f(x) is replaced with 3f(x)? a) shifts the line 3 units up b) shifts the line 3 units down c) increases the slope of the line by a factor of 3 d) decreases the slope of the line by a factor of 3

Olivia uses the work below to determine 55% of 720 which explains the error in olivia’s solution