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

a) Select appropriate variables.

b) Write the objective functions.

c) Write the constraints as inequalities.

d) Solve the problem.