Let x be the base square dimension, in centimeters. Then the bottom base has the area, and the same for the top base. The lateral surface area is 4*x*10 = 40x. Therefore, your equation for the total surface area is = ---> = 0. Use the quadratic formula to solve this quadratic equation. You will get the only positive root x = 15 cm. Check. = 450 + 600 = 1050 cm^2. Correct. Answer. The volume is = 3375 liters.