Question 750867
We can solve this with just one variable. 
The short side is X, the long side is X+20

(X)(X+20)=1150

{{{X^2+20X=1150}}}

{{{X^2+20X-1150=0}}}

The quadratic solver yields 

*[invoke quadratic_formula 1, 20, -1150, "x"]

And the first answer is positive. The second side is 20 feet longer.