Let f(x)=15x-and let R be the region bounded by the graph of f and the x-axis on the interval [0,5]. a. Find the area of the surface generated when the graph of f on (0,5] is revolved about the x-axis. b. Find the volume of the solid generated when R is revolved about the x-axis. a. Find the area of the surface. 94.2478 square units. (Type an exact answer, using x as needed.) b. Find the volume of the solid. 85.87 cubic units. (Tynn an exact answer, using x as needed.)