A bank wishes to invest a $100,000 trust fund in three sources: a bond fund paying 8%; a health sciences fund paying 7%; and a real estate fund paying 10%. The bank wishes to realize an $8000 annual income from the investment. A condition of the trust is that the total amount invested in the bond fund and the health sciences fund must be triple the amount invested in the real estate fund. How much should the bank invest in each possible category?