Answer
$\approx 4.467\times 10^{23}$ ergs
Work Step by Step
Substitute the given R=7.9 into
$ R=\displaystyle \frac{2}{3}(\log E-11.8), \qquad$ and solve for E
$7.9=\displaystyle \frac{2}{3}(\log E-11.8)$
$\displaystyle \frac{3(7.9)}{2}=\log E-11.8$
$\displaystyle \log E=\frac{3(7.9)}{2}+11.8$
$\log E= 23.65$
$E=10^{23.65}\approx 4.467\times 10^{23}$ ergs
