Question 201096
Let the length = L and the width = W.
The area of a rectangle is given by:
{{{A = L*W}}} Substitute L = W+20 and A = 4800.
{{{4800 = (W+20)W}}} Simplify.
{{{4800 = W^2+20W}}} Subtract 4800 from both sides.
{{{W^2+20W-4800 = 0}}} Solve by factoring.
{{{(W-60)(W+80) = 0}}}Apply the zero product rule.
{{{w-60 = 0}}} or {{{W+80 = 0}}} so that...
{{{W = 60}}} or {{{W = -80}}} Discard the negative solution as width can only be positive.
The width is 60 feet and the length is 60+20 = 80 feet.