Let us start with the schnauzers, the easiest one to imagine. Let us assume that there were x number of schnauzers. Scottie's are 3 more than schnauzers. So their number is x+3 Wire haired terriers are 5 less than twice the number of schnauzers. So their number is 2x -5 (2x for twice the number of schnauzers) Now add all these numbers. That is x + x+3 + 2x-5 = 4x -2 The total number of dogs, 78, is given in the question Now we know that 4x -2 =78 4x = 78 +2 = 80 Therefore x = 80/4 = 20. So there were 20 schnauzers, 23 Scottie’s and 35 wire haired terriers