Math! (Middle School, IK how to do this, but I’m lazy and I need also need to do something...)

Answer:
I only know the answer to the first question so uh yea.
answer: 792
Step-by-step explanation:
determine area of square: 11x15x24=3960
take away 1/5 of the area (to do this find the decimal form of the fraction and multiply that by the area): 3960x0.2=792