The energy of second orbit of hydrogen atom is $-5.45\times {10}^{-19} \mathrm{J}$. What is the energy of first orbit of ${\mathrm{Li}}^{2+}\text{ ion (in }\mathrm{J}\text{ ) }$?

$$\begin{gathered} \mathrm{E}=-13.6\left(\frac{{\mathrm{z}}^2}{{\mathrm{n}}^2}\right) \\ \mathrm{Second} \mathrm{orbit} \mathrm{of} \mathrm{H}: \\ -5.45\times {10}^{-19}\mathrm{J}=-13.6\left(\frac{1^2}{2^2}\right)...\left(1\right) \\ \mathrm{First} \mathrm{orbit} \mathrm{of} {\mathrm{Li}}^{2+} \\ \mathrm{E}=-13.6\left(\frac{3^2}{1^2}\right)...\left(2\right) \\ \mathrm{Equate} \left(1\right) \mathrm{and} \left(2\right): \\ \frac{-5.45\times {10}^{-19}\mathrm{J}}{\mathrm{E}}=\frac{-13.6\left(\frac{1^2}{2^2}\right)}{-13.6\left(\frac{3^2}{1^2}\right)} \\ \mathrm{E}=-1.962\times {10}^{-17} \mathrm{J} \end{gathered}$$