Numerical Methods: Euler to Runge–Kutta · Easy problem

To use Euler's method on $y'' = t - y$, $y(0) = 1$, $y'(0) = 2$, write it as the system $u' = v$, $v' = t - u$ with $u = y$, $v = y'$. Take one Euler step with $h = \dfrac{1}{2}$. What is the resulting estimate of $y'\left(\dfrac{1}{2}\right)$? Express your answer as a common fraction.