Question

an investor is considereing three types of investment: a high-risk venture into oil leases with a potential return of 15%, a medium risk investment in bonds with a 9% return, and a relatively safe stock investment with a 5% return. He has $50,000 to invest. Because of the risk; he will limit his investment in oil leases and bonds to 30% and his investment in oil leases and stock to 50%. How much should he incest in each to maximize his returns assuming investment returns are as expected?