A mixture contains 1 mole of helium

A mixture contains 1 mole of helium $\left(C_{p}=2.5 R, C_{v}=1.5 R\right)$ and 1 mole of hydrogen $\left(C_{p}=3.5 R, C v=2.5 R\right)$. Calculate the values of $C_{p}, C_{v}$ and $\gamma$ for the mixture.