Question 42113
Let length = x inches.
Then, width = (x - 4) inches.
Thus perimeter = 2(Length + Width) = 2(x + (x - 4)) = 2(2x - 4) = 4(x - 2) inches.
But it is given that perimeter = 420 inches.
So 4(x - 2) = 420
or x - 2 = {{{420/4}}} = 105
or x = 105 + 2 = 107.


Hence, reqd. length is 107 inches.