[tex]\frac{3}{5}=\frac{x}{x+2y}\ \ \ \ \ |cross\ multiply\\\\3(x+2y)=5(x)\\3(x)+3(2y)=5x\\3x+6y=5x\ \ \ \ \ |subtract\ 3x\ from\ both\ sides\\6y=2x\\2x=6y\ \ \ |divide\ both\ sides\ by\ 2\\x=3y\ \ \ \ |divide\ both\ sides\ by\ y\\\boxed{\frac{x}{y}=3}[/tex]