Answer:
120 boats
Step-by-step explanation:
The number of boats is a multiple of 5 and also a multiple of 6 so it is a multiple of 5x6=30. Is 30 the answer? One sixth of 30 is 5 and three fifths of 5 is 3 so this would give 3 red boats. But there are 12 red boats so the number of boats must be 4 times 30 or 120. Check that 120 is correct. One sixth of 120 is 20 and three fifths of 20 is 12 so 120 is the correct answer.