How do I set this problem up for Excel:
A National Credit Union has $250,000 available to invest in a 12 month commitment. The money can be placed in Treasury notes yielding an 8% return or in mubnicipal bonds at an average rate of return of 9%. Credit uniion regulations require diversification to the extent that at least 50% of the investiment be placed in Treasury notes. Because of defaults in other municipalities, it is decided that NO MORE than 40% of the investiment be placed in bonds. How much should the credit union invest in each security so as to maximize its return on investment?