Question

HELP PLEASE BECAUSE KHAN ACADEMY SUCKS!

Answer 1

I think it’s 10 cm
Don’t know if I’m right tho

Answer 2

volume Large Can
r = 8 cm
pi = 3.14
h = 20 cm
V = pi r^2 h
V = 3.14*8^2 * 20
V = 4019 cm^3

Volume left over.
He has 1/4 of a can of  paint left.
V1 = 1/4 * 4019
V1 = 1004.8

Calculate height.
V = 1004.8
pi = 3.14
r = 5 cm^2
h = ??

h = V/(pi r^2)
h = 1004.8 / (3.14 * 5^2)
h = 1004.8 / 78.5
h = 12.8 cm

There are other ways of doing this, but this is the clearest.