The question is worded poorly, but it looks like you have a lever in equilibrium, with a force x at a distance d from the fulcrum, and a force y at a distance L - d from the fulcrum. You already have the equilibrium formula for this situation:
xd = y(L - d)
If you know x, y, and d, you can solve for the length L.
Let x= width
Length= 5x-4
2(x)+2(5x-4)=160
2x+10x-8=160
12x-8=160
+8. +8
12x=168
x=14
width=14
length= 5(14)-4=66
Yes the quotient of 9 is rational
