A matrix question on the Gaussian elimination method?

Hey,

I’ve been stuck on the below question for a while now, and I’m not sure where I’m going wrong.

A bank wishes to invest a $110,000 trust fund in three sources: bonds paying 9%; certificates of deposit paying 8%; and first mortgages paying 13%. The bank wishes to realize an $10,425 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.

Thanks for your help!