[tex]m=\frac{E}{c^{2}}[/tex]
1) In this literal equation problem, let's perform some algebraic manipulations:
[tex]\begin{gathered} E=mc^2 \\ \frac{E}{m}=\frac{mc^2}{m} \\ c^2=\frac{E}{m} \\ mc^2=E \\ \frac{mc^2}{c^2}=\frac{E}{c^2} \\ m=\frac{E}{c^{2}} \end{gathered}[/tex]
Note that the point here is to isolate m on the left side, so we needed to divide both sides and then cross multiply them.
