$4800 is invested in two different accounts. One account pays 27% simple interest per year and the other account pays 11% simple interest per year. If the total interest earn in one year is $672.00, how much is invested at each rate?

Let $LaTeX: \displaystyle x$ be the amount invested at 27%. Then $LaTeX: \displaystyle 4800-x$ is amount invested at 11%. This gives the equation $LaTeX: \displaystyle 0.27 x+0.11(4800 - x)=672$ . Solving for $LaTeX: \displaystyle x$ gives $LaTeX: \displaystyle x = 900$ . So the amount in the other account is $3900.