Please help me solve this word problem

Question

Miss Powell is building a retaining wall along one of the sides of her rectangular garden. The garden is twice as long as it is wide. It also has an area of 620 square feet. What will be the length of the retaining wall?

Answer 1

Let L = length of garden 

Let W = width of garden 

 

Twice as long as wide  ==>  L = 2*W

 

Area 620  ==>  L*W = 620

 

Substitute the value for L from the 1st equation into the 2nd equation 

 

(2*W)*W = 620

W^2 = 310

W = +- sqrt(310) 

 

Width cannot be negative so discard the negative solution 

 

W = sqrt(310) ~ 17.6 feet

 

L = 2*sqrt(310) ~ 35.2 feet 

 

The retaining wall will be either 17.6 feet or 35.2 feet depending on whether Miss Powell builds it along the width or length of her garden.