Let's check your answer:
[tex]\begin{gathered} f(x)=3(6^{\text{ -x}}) \\ f(1)=3(6^{\text{ -1}})=3(\frac{1}{6})=\frac{3}{6}=\frac{1}{2} \\ \\ f(2)=3(6^{\text{ -2}})=3(\frac{1}{6^2})=3(\frac{1}{36})\text{ = }\frac{1}{12} \\ \\ f(3)=3(6^{\text{ -3}})=3(\frac{1}{6^3})=3(\frac{1}{216})=\frac{3}{216}=\frac{1}{72} \\ \end{gathered}[/tex]Your answer is correct.
