tolong bantu saya mengerjakan soal ini nomor 4,5,6 please.....

4. 88 l = 88 dm^3 = 88000 cm^3
V.tabung=phi x r^2 x t
= 22/7 x r^2 x 70
= 220 x r^2
220 x r^2 = 88000
r^2 = 88000 : 220
r^2 = 400
r = 20 cm
5. V.kerucut = 1/3 x phi x r^2 x t
d = 2r
12 = 2r
12 : 2= r
r = 6
1/3 x phi x 6^2 x 21
7 x phi x 36
252 phi
22/7 x 252
22 x 36
V = 792 cm^3
6. gk ngerti sama bahasanya, sorry