4. 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 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% (of the $50,000 ) and his investment in oil leases and stock to 50%. How much should he invest in each to maximize his return, assuming investment returns are as expected? a. Define the variables. Be specific with descriptive words. x1=x2= x3= b. Clearly state the constraints (all inequalities) related to the feasible region. c. State the objective function