All you need to do is convert all equations into standard form by using the distributive property on each equation.
It is 26635.2384 because you multiply the pi times the radius18.8 to the 2nd power times the height that is 24
This isnt something I can do... But draw and label a tape diagram that goes from 0 to 30.
30(-2/5)²(5/8) = 30*(4/25)*(5/8) = 30*4/(5*8) = 3