(5x)/(x+y)+(5y)/(x-y)+(10xy)/(x^2-y^2)=
(5x^2-5xy+5xy+5y^2)/(x^2-y^2)+(10xy)/(x^2-y^2)=
(5x^2+5y^2+10xy)/(x^2-y^2)
x/(x+y)+y/(x-y)-2xy/(x^2-y^2)=(x^2-xy+xy+y^2-2xy)/(x^2-y^2)=(x^2-2xy+y^2)/(x^2-y^2)=
(x-y)^2/((x-y)*(x+y))=(x-y)/(x+y)
((5x^2+5y^2+10xy)/(x^2-y^2))*((x-y)/(x+y))=
(5*(x^2+2xy+y^2)*(x-y))/((x-y)*(x+y)*(x+y))=(5*(x+y)^2*(x-y))/((x+y)^2*(x-y))=5