The sum of −7 and the quotient of m and n.

V=1300π ft

Step-by-step explanation:

The formula for the volume of a cylinder is V=πr^2h, so you need to find the correct values so you can plug them in.  The radius is diameter divided by 2, (diameter being the line across the circle,) and the diameter is 20ft, so the radius is 10ft.  Now you can plug the values into the formula, getting V=π10^2(13).  Square 10 to get V=π100(13), then multiply 100 by 13 to get V=π1300.  Since you want the exact value, the answer is 1300π ft.