## Elementary Algebra

The interest formula is: i = P $\times$ r $\times$ t. To find the principal, or P, we divide i by r $\times$ t. So, P = $\frac{i}{r\ \times\ t}$ i = 540 r = 6% = 0.06 t = 2 Substitute these values into the formula to find out the principal needed. P = $\frac{540}{0.06\times 2}$ P = $\frac{540}{0.12}$ P = 4500 4500 dollars is needed.