## Elementary Algebra

Let X represent the amount of fertilizer needed for 2500 square feet. Now, let’s set up a proportion in which one ratio compares the amounts of fertilizer, and the other ratio compares the surfaces covered. So, $\frac{20}{X}$ = $\frac{1500}{2500}$. We cross multiply to obtain: 20 $\times$ 2500 = X $\times$ 1500 50000 = 1500X X = 33.3333