Momentum will be conserved
\(0=x v_1+y v_2\)
\(-x v_1=y v_2 \ldots (1)\)
\(\frac{k_1}{k_2}=\frac{\frac{1}{2} x v_1^2}{\frac{1}{2} y v_2^2}\)
Using \((1)\) \(\left(\frac{v_1}{v_2}\right)^2=\frac{y^2}{x^2}\)
\(\frac{k_1}{k_2}=\frac{x}{y} \cdot\left(\frac{y^2}{x^2}\right)\)
\(=\frac{y}{x}\)