Answer :
Volume = (4/3) * PI * radius^3
80 * PI = (4/3) * PI * radius^3
The 'PI's' cancel out leaving
80 = (4/3) * radius^3
radius^3 = 80/(4/3)
radius^3 = 60
radius = cube root (60)
80 * PI = (4/3) * PI * radius^3
The 'PI's' cancel out leaving
80 = (4/3) * radius^3
radius^3 = 80/(4/3)
radius^3 = 60
radius = cube root (60)