Question 173103
The length of a rectangular park is 2 times greater than its width.
The park is framed by sidewalk that is 2 m wide.
The area of the park is increased by 136m square if the sidewalk is included.
What is the area of the park without the surrounding sidewalk ? 
.
area of sidewalk is 136 sq m
.
"area of park plus walk" is
.
Park measurements:
Let w = width of park
then
2w = length of park
.
Park plus walk measurements:
w+4 = width
2w+4 = length
.
(w+4)(2w+4) - w(2w) = 136
2w^2+4w+8w+16 - 2w^2 = 136
4w+8w+16 = 136
12w+16 = 136
12w = 120
w = 10 m (width)
.
Length:
2w = 2(10) = 20 m(length)