Answer: 3.5% with a 3.50 Tip
Reason: 25.00 - 21.50 = 3.50
I can’t see the pic sorry
Area of Trapezoid = h(b1+b2/2)
b1 and b2 are the lengths of each base and h is the height.
Area = 16(20+24/2)=352 Square Feet
352/20=17.6 Cans of paint.
Hope this helps and is correct, I haven't done this kind of math in a while.