p:l:t = 5:3:3. Jika volume balok tersebut 1.920 cm2, maka luas alasnya adalah...

V = p.l.t 
1920 = (5x).(3x).(3x)
1920 = 45x³
[tex] \frac{1920}{45} [/tex] = x³
42,67 = x³
3,49 = x

Luas alas = p.l = 5(3,49) . 3(3.49) = 17,45 + 10,47 = 27,92 cm²