The area of a rectangular floor is 72 ft2. The length of the floor is 1 ft more than 3 times the width. How wide is the floor (rounded to the nearest whole number)?

Answer 1

area = width * length

length = 1+3*width

area = width * (1+3*width)
72 = w(1+3w) = w + 3w²
3w² + w - 72 = 0
w = (-1 + sqrt(865))/6 = 4.7

so, rounding up, w = 5'