I need help figuring out this math question please ?

Question

A rectangular sandbox is surrounded on all sides by a strip of grass that is 5 feet wide on all sides. The length of the sandbox is 4 feet more than the width, and the total area for the sandbox and the grass is 190 square feet. Find the dimensions of the sandbox.

The length of the sandbox is ?

and the width is ?

Answer 1

Let the sandbox width = W and the length L = W+4

The condition for the grass and the sandbox is modeled by (W+10)(W+4+10) = 190 or

(W+10)(W+14) = 190 = W2 + 24W + 140 or w2 + 24W -50 = 0

The roots are W = -25.93 and 1.93 So the real answer for W = 1.93, Therefore, L = W+4 = 5.93