Answer
$$S = \$ 278,150.87$$
Work Step by Step
$$\eqalign{
& R = \$ 9000,\,\,\,\,\,i = 0.06,\,\,\,\,\,{\text{ and }}n = 18 \cr
& {\text{The amount }}S{\text{ of an annuity of payments of }}R{\text{ dollars each}}{\text{, made at the }} \cr
& {\text{ end of each period for n consecutive interest periods at a rate of interest}} \cr
& {\text{ }}i{\text{ per period}}{\text{, is given b}}y \cr
& S = R\left[ {\frac{{{{\left( {1 + i} \right)}^n} - 1}}{i}} \right] \cr
& {\text{Substituting }}R,\,\,\,i{\text{ and }}n \cr
& S = \$ 9000\left[ {\frac{{{{\left( {1 + 0.06} \right)}^{18}} - 1}}{{0.06}}} \right] \cr
& {\text{Simplify by using a calculator}} \cr
& S = \$ 9000\left( {30.9056} \right) \cr
& S = \$ 278,150.87 \cr} $$
