There are 66 neutrons in a single atom of indium-115. The atomic number of indium-115 is 49, meaning there are 49 protons. Then the atomic mass is 115, so 115-49 = 66.
The molar mass of Allicin is 162 which means that you can just divide 64 by 162 since 64 is the mass of sulfur in 1 mole of Allicin (32×2=64). You should get 0.395 which is 39.5%