Question 174982
The width of the park is w and thelength is l.

The equations that describe the situation are:

2l+2w=1280m (Equation #1)

w = (1/2)*l+70 (Equation #2)

Equation #1 can be rewritten as l = 640 - w

Substitute the value for l into equation #2

w = 1/2(640-w)+70 = 320 -(1/2)*w + 70

Putting the unknowns on one side of the quation.

w+(1/2)w=390

3/2w = 390

Solve for w  

w = 390*(2/3) = 260 m

Substituting the value for w into equation #1, we have

2*l+2*(260m)=1280m

2*l = 1280m-520m = 760m

Solve for l

l = 380m