Gamma parameters from mean and variance

Let $X$ be a random variable with the probability density function

$$f(x)=\begin{cases}\dfrac{\alpha^p}{\Gamma(p)}e^{-\alpha x}x^{p-1}, & x\ge0, \alpha>0, p>0,\ 0, & \text{otherwise.}\end{cases}$$

If $E(X)=20$ and $Var(X)=10$, then $(\alpha,p)$ is