W=width, L=length
L=2W-7
LxW=99 (now substitute)
(2W-7)xW=99 (distribute W)
2W²-7W=99
2W²-7W-99=0 (set to 0 to solve)
(W-18/2)(W+9/2)=0
(W-9)(2W+9)=0
W-9=0; W=9
2W+9=0; 2w=(-9) not possible in real world to have a negative length
So, width = 9 ft, and length = 2(9)-7 = 11 ft