Jawabanmu

2014-05-08T14:22:35+07:00
Alas Limas =  21cm^2
1/3*luas alas * tinggi = Volum
1/3 * 21 * t = 84
7t = 84
tinggi = 84/7 = 12cm

2014-05-08T14:26:34+07:00
P=7  , l = 3
 V = luas alas x t
84 = 21 x t
t = 4