conservation law for the trajectories Is it possible to find the conservation equation as the form of $Q=h(x,y)$, given that $$\dot{x}=x-xy$$ $$\dot{y}=5xy-5y$$ I am not sure how to start with.

"Divide" one equations by another and find a separable equation $$ \frac{dy}{dx}=\frac{5xy-5y}{x-xy},\, $$ integrate.