A tiffin box contains x pink and (x – 4) yellow toffees and another tiffin box contains (x – 1) yellow and (x – 3) pink toffees. If one of the tiffin box is selected at random and 2 toffees are drawn at random from the box thus selected, the probability that the two toffees are of different colours is 67/132. Find the total number of toffees in the first tiffin box?