Question 389116
{{{x*y=60}}}
{{{x^2+y^2=13^2}}}

{{{x^2+y^2+2(x*y)=13^2+2(x*y)}}}
{{{(x+y)^2=13^2+120}}}
{{{(x+y)^2=169+120}}}
{{{(x+y)^2=289}}}
{{{(x+y)= 17}}}
{{{x=5}}}
{{{y=12}}}