A water trough is in the shape of a rectangular solid. The length of the trough is 4 times its width, and its depth is 5 feet. A new trough is constructed with length 4 feet greater than the length of the original trough, a width 1 foot less than the width of the original trough and a depth equal to that of the original trough. If the capacity of the new trough is 300 cubic feet, what is the capacity, in cubic feet, of the original trough?