The binding energy of an element is 64 MeV. If BE/nucleon is 6.4, then the number of nucleons are :
The binding energy of deuteron (21H) is 1.15 MeV per nucleon and an alpha particle (42He) has a binding energy of 7.1 MeV per nucleon. Then in the reaction 21H+21H→42He+Q the energy Q released is