$3^{3}\timesx-1=243$
$=>27\timesx=243+1$
$=>27\timesx=244$
$=>x=244:27$
$=>x=\dfrac{244}{27}$
\(3^{3\times x-1}\) = 243
3\(^{3\times x-1}\) = 35
3 \(\times\) \(x\) - 1 = 5
3 \(\times\) \(x\) = 5 + 1
3 \(\times\) \(x\) = 6
\(x\) = 6 : 3
\(x\) = 2