Solve the problem.
The volume of a rectangular box with square base and a height of 5 feet is V(x) = 5x2, where x is the length of a side of the base. Find the instantaneous rate of change of volume with respect to x when x = 3 feet.
◦ 15 ft3/ft
◦ 45 ft3/ft
◦ 6 ft3/ft
◦ 30 ft3/ft