tolong dijawab mau un soalnya beserta caranya

Volume= v awal ×2×2×3
20×2×2×3
240 dm3

volume = 1/3 x pi x r^2
20 = 1/3 x pi x r^2 x t
20 = 1/3 x 22/7 x r^2 x t
20 = 22/21 x rt
    = (22/21 x r^2t) : 20

volume = 1/3 x 22/7 x 2r^2 x 3t
volume = 22/21 x 4r x 3t
volume = 22/21 x 12 rt

(22/21 x rt) : 20 = 22/21 x 12 rt   (coret yang sama)
             rt/20 = 12 rt
                      = 12 rt x 20/rt = 240 dm^3