LINEAR SYSTEMS Solving A Tax Rate

Last year, Tony had $10,000 to Invest. He Invested some of It In an account that paid 5% simple Interest per year, and he Invested the rest in an account that
pald 9% simple Interest per year. After one year, he received a total of $820 In Interest. How much did he Invest In each account?
Note that the ALES graphing calculator can be used to make computations easler.