lenght of a garden

Question

the area of a rectanglular garden is 640 ft square. the sum of the width and twice the length is 72 feet. find the possible length of the garden

Answer 1

Let x = the width

Let y = the length

x + 2y = 72      x = 72 - 2y

A = lw

640 = y(72-2y)

640 = 72y - 2y²

2y² - 72y + 640 = 0

y² - 36y + 320 = 0

(y - 20)(y - 16) = 0

y - 20 = 0       or     y - 16 = 0

y = 20 feet    or     y = 16 feet