Investment Strategy Problem
A company reserved $30 million for investments. The money is to be divided among treasury notes, stocks, and bonds. It is required that at least $3 million be invested in each type of investment, and at at least $15 million be invested in treasury notes and bonds, while the amount invested in bonds cannot exceed twice the amount invested in treasury notes.
It is known that the annual yield for treasury notes is 7%, for stocks 9%, and 8% for bonds. What is the maximum return attainable by the given requirements in millions of dollars?