Answer
See below.
Work Step by Step
A physicist finds the mass per nucleon of the starting nucleus/nuclei and the mass per nucleon of the product(s) after the reaction (for either a fission or a fusion reaction). This is done using the curve shown in Figure 34.16 or from a table of nuclear masses.
There will be mass "lost", which was transformed into energy. Multiply this mass difference by the speed of light squared to calculate the energy released: $E = mc^{2}$.
