Let x represents the amount invested at 5% annual interest, and let y be the amount invested at 10% annual interest. The system of equations is x + y = 150000 dollars (1) 0.05x + 0.10y = 12000 dollars (2) Equation (1) says that the total invested amount of the two accounts is $150,000. Equation (2) says that the total annual interest of the two accounts is $12,000.