SOLUTION:
[tex]f(t)=a(1-\frac{r}{100})^t\text{ }[/tex]Where a = Initial amount ($200), r = rate (7%) and t = time (20 years).
[tex]\begin{gathered} f(20)\text{ = 200 ( 1 - }\frac{7}{100})^{20} \\ f(20)=200(1-0.07)^{20} \\ f(20)\text{ = 200 (}0.93)^{20} \\ f(20)\text{ = 200 (0.2342)} \\ f(20)\text{ = 46.84 ( nearest cents)} \end{gathered}[/tex]CONCLUDSION:
The cost of the item after 20 years will be 46.84 cents.