Betty plans to invest a total of $12,000 in mutual funds, certificates of deposit (CDs), and a high-yield savings account. Because of the risk involved in mutual funds, she wants to invest no more in mutual funds than the sum of her CDs and savings. She also wants the amount in savings to be at least half the amount in CDs. Her expected returns are 11% on the mutual funds, 8% on the CDs and 6% on savings. How much money should Betty invest in each area in order to have the largest return on her investments? Set this up as a linear programming problem in the following form: Maximize c^Tx subject to Ax ≤ b and x ≥ 0. Do not find the solution.