$10500 is invested in two different accounts. One account pays 13% simple interest per year and the other account pays 26% simple interest per year. If the total interest earn in one year is $2210.00, how much is invested at each rate?

Let $LaTeX: \displaystyle x$ be the amount invested at 13%. Then $LaTeX: \displaystyle 10500-x$ is amount invested at 26%. This gives the equation $LaTeX: \displaystyle 0.13 x+0.26(10500 - x)=2210$ . Solving for $LaTeX: \displaystyle x$ gives $LaTeX: \displaystyle x = 4000$ . So the amount in the other account is $6500.