A rectangular plot is 30 feet long and 20 feet wide. The area will be doubled by adding a strip at one end and another strip of the same width on one side. What would be the width of the strip?

Answer 1

A = L*W = 30 * 20 = 600F^2.

Width = X feet.
A = (30+X) * (20+X) = 1200F^2,
600 + 30X + 20X + X^2 = 1200,
X^2 + 50X + 600 = 1200,
X^2 + 50X - 600 = 0,

(X-10)(X+60) = 0,
X - 10 = 0,
X = 10.

X+60 = 0,
X = - 60.

Select the + value of X:
X = 10 Feet.