Measurements for a fence

Question

A rectangular area is to be fenced and along a straight riverbank as illustrated. the length of the fence in area is to be 3 ft greater than the width and the total amount of the fixing to be used is 69 ft. find the width and the length of the fence in the area

Answer 1

w = width of rectangle

l = length of rectangle

l = w+3 (the length of the fence in area is to be 3 ft greater than the width)

Although it is a rectangular shape, only three sides need to be fenced because one side runs along the river.

(I don't have a picture, but I assume the missing length is the side by the river.)

2w+l=69

Substitute l=w+3 into the equation

2w+(w+3)=69

3w+3=69

3w = 66, so divide both side by 3

w=22 ft

l=w+3 = 22+3 = 25 ft