The average annual return over a certain 5 year period of 3 different mutual funds offered by Franklin Templeton is shown in the table below. Suppose you have $6000 to invest in these 3 funds. You will invest $200 more in the High Income fund than you will in the Conservative fund. How much should you invest for a year in each fund if you want your average annual return to be 7%? Set up 3 equations and use matrix algebra to find the solution.

I do not understand how to use the matrix algebra to solve the equations.

for my equations I got x+y+z= 6000, x-y=200, and 0.1382x +0.0536y + 0.04052z= 0.07(600). basically I don't know how to type this into my calculator.
 

Mutual Fund Average Annual Return High Income 13.82% Conservative 5.36% 4.05% Mutual Shares