Total number of structural isomers possible with the formula, C3H4 is ‘X’. Total number of acyclic structural isomers possible with the formula, C3H4 is ‘Y’. Sum of X and Y is equal to

Number of alkynes = 1 ;Number of alkadienes (cumulative dienes) = 1 ;Number of acyclic isomers = 2 ;Number of cycloalkenes = 1 ;Number of cyclic isomers = 1 ;Number of acyclic structural isomers = 2 ;Number of acyclic stereo isomers = 0 ;Number of cyclic structural isomers = 1 ;Number of cyclic stereo isomers = 0 ;Total number of  structural isomers = 3 ;Total number of  stereo isomers = 0 ;Total number of isomers = 3 ;