The correct answer to this question is 63. To answer this question, start with the data you are given. On Saturday, Jack caught 14 fish. He caught twice as many fish on Sunday, so take 14 times 2 to find the "doubled" amount - 28 fish.
To recap, Jack caught 14 fish on Saturday and 28 fish on Sunday. On Monday, Jack caught half the number of the total fish he caught on Saturday and Sunday, so take 14 plus 28 (equals 42 for both days) and divide by 2. This equation gives you 21 fish for Monday. Finally, add all three totals together: 14 + 28 + 21 = 63.