Writing this info out symbolically:
x^2 + (x+5)^2 = 37
Expanding, x^2+x^2+10x +25=37, or 2x^2+10x-12=0.
Reducing, x^2+5x-6=0. factoring, (x-1)(x+6)=0
Solving for x: x-1=0 results in x=1; x=6=0 results in x=-6.
We want only a positive result, so choose x=1 and discard x=-6.