Look at the coefficient, and then convert the mol to gram by using the molar mass.
CH3NH3Cl + NaOH ---> CH3NH2 + NaCl + H2O
mol: 1mol 1mol
gram: 67.5 g 31 g
Thus, according to the reaction 67.5 g CH3NH3Cl is required to produce 31 g CH3NH2. Based on this ratio,
(67.5 g CH3NH3Cl/31 gCH3NH2) x 0.63 g CH3NH2 = 1.37 g CH3NH3Cl were used up.