Hi, I need help solving some questions

A box without a lid will be constructed from a 75 cm by 100 cm piece of cardboard, by cutting squares of the same size from each corner, and folding up the sides. What is the approximate volume of the largest possible box that can be constructed? O 47, 380 cm3 105, 000 cm3 O 60, 000 cm3 O 30, 000 cm3 4.5 points Which of the following models could be used to find two numbers whose sum is 256, but whose product is a maximum? O f(x) = x (256 - x) O f (20) - 20 (20 - 256) y = 116 - x O f ( x) = xy