## Elementary Algebra

The interest formula is: I = P $\times$ r $\times$ t. To find the time needed to invest, or t, we divide I by P $\times$ r. So, t = $\frac{I}{P\ \times\ r}$ P = 2000 r = 5.4% = 0.054 I = 162 Substitute these values in the formula to obtain: t = $\frac{162}{2000\ \times\ 0.054}$ t = $\frac{162}{108}$ t = 1.5 hours