One of my hw questions I can't quite figure out:

Debt of $3500 due in 4 years and $5000 due in 6 years is to be repaid in a single payment of $1500 now and 3 equal payments that are due each consecutive year from now. If the interest rate is 7% compounded annually, how much are each of the equal payments?

It would be nice if someone could explain how to answer the question instead of just giving the answer but any help is appreciated