\(x \propto \frac{1}{y}\)

\(x = \frac{k}{y}\)

\(y \propto t^{2}\)

\(y = ct^{2}\) 

k and c are constants.

\(x = \frac{k}{ct^{2}}\)

Let \(\frac{k}{c} = d\) (a constant)

\(x = \frac{d}{t^{2}}\)

\(1 = \frac{d}{3^{2}} \implies d = 9\)

\(\therefore x = \frac{9}{t^{2}}\)

\(x = 9 \div (\frac{1}{3})^{2} \)

= \( 9 \div \frac{1}{9} = 9 \times 9 = 81\)