Question 166235
L=length=2W-8   W=width   diagonal makes to right triangles so

by the pathorean theorem {{{(2W-8)^2+(W^2)=20^2)}}} multiply this out-simplify

{{{5W^2-32W-336}}} using the quadratic formula we get W=12 and -5.6

throw out the negative value

so W=12  and L=2(12)-8=16