Give the step-by-step reasoning process and then the final answer. Ali, Peter, and Joey were fishing. The fish Ali caught weighed, in sum, twice as much as the fish that Peter caught. Joey caught 1 kg more fish than Peter. Together the three of them caught 25 kg of fish. How many kilograms did Ali catch?
Let x be the weight of the fish that Peter caught. Then Ali and Joey caught 2 * x and x + 1 kg of fish, respectively. So, x + 2 * x + x + 1 = 25. So, 4 * x = 25 - 1 = 24. So, x = 6. Therefore, Ali caught 2 * x = 2 * 6 = 12 kg of fish.
The final answer: 12.