Numerical Methods: Euler to Runge–Kutta · Medium problem

For $y' = y$, $y(0) = 1$, compare one Euler step to one step of the midpoint method (RK2), both with $h = 0.2$. Midpoint: $k_1 = f(t_0, y_0)$, $k_2 = f\!\left(t_0 + \dfrac{h}{2},\ y_0 + \dfrac{h}{2}k_1\right)$, $y_1 = y_0 + hk_2$. Since both estimates approximate the same unknown $y(0.2)$, the gap between them is a direct measure of the extra accuracy the midpoint method buys over Euler here. Find the midpoint estimate minus the Euler estimate. Express your answer as a common fraction.