A bank wishes to invest a $180,000 trust fund in three sources: bonds paying 12%; certificates of deposit paying 10%; and first mortgages paying 16%. The bank wishes to realize an $21,500 annual income from the investment. A condition of the trust is that the total amount invested in bonds and certificates of deposit must be triple the amount invested in mortgages. How much should the bank invest in each possible category? Let x, y, and z, respectively, be the amounts invested in bonds, certificates of deposit, and first mortgages. Solve the system of equations by the Gauss-Jordan elimination method.