Numerical Methods: Euler to Runge–Kutta · Easy problem

The problem $y' = 2t$, $y(0) = 0$ has exact solution $y = t^2$. One Euler step with $h = \dfrac{1}{5}$ is taken from $t = 0$. Find the local error, the exact value $y\left(\dfrac{1}{5}\right)$ minus the Euler estimate. Express your answer as a common fraction.