# Quantum Mechanics: Eigenvaules, and orthogonality

Hey, I've been trying to solve this problem it sounds simple but i don't know where to start:

If $$\phi_{1}$$ and $$\phi_{2}$$ are normalised, have the same eigenvalue and obey $$\int \phi_{1}*\phi_{2}d\tau = c$$ find the linear combination that is normalised and orthogonal to $$\phi_{1}$$

Thanks