Set up an equation and solve the following problem.
The length of a rectangular floor is 8 meter less than twice its width. If a diagonal of the rectangle is20 meters, find the length and width of the floor.
a. width is 12 m, length is 16 m
b. width is 24 m, length is 32 m
c. width is 14 m, length is 18 m
d. width is 10 m, length is 15 m
e. width is 11 m, length is 17 m