I removed your other post since it is the same question. No Cross posting if you please.
Anyway, which equation has the most pnegative (less positive) reduction potential? Whicheverone you choose will need to be reversed and the reduction potential will change signs (now it is an oxidation reaction. You then need to balance elctrons by multiplying the botom equation by 5. That way when you add them, the elctrons cancel out. This also gives you the appropiate "n" value for calculating the delta G.