tolong dijawab pake cara

P1 = P2
F1 / A1 = F2 / A2
80 / π.(r1)^2 = 500 / π.(r2)^2
(r1)^2 / (r2)^2 = 80 / 500
(r1)^2 / (r2)^2 = 4 / 25
r1 / r2 = 2 / 5