Existence, Uniqueness & Bifurcations · Medium problem

A logistic population with proportional harvesting obeys $y' = 2y\left(1 - \dfrac{y}{50}\right) - Ey$, where $E \ge 0$ is the fishing effort. At what effort $E$ does the equilibrium $y = 0$ change from unstable to stable (a transcritical bifurcation)?