The cover of a rectangular swimming pool is 500 square feet. if the length is 10 feet less than four times the width, what is the perimeter of the pool

So the length is 4w-10 and the width is just w, the area (the cover) is

(4w-10) (w) = 500. So when you multiply it out you get 4w²-10w=500. When you solve for that you get that w is 12.5, - 10 but since it is a measurement, it needs to be positive so w=12.5. Substituting that back into the equation, ((4) (12.5) - 10) = 40. So 40+40+12.5+12.5 = 95.