If there are sixty-five dolphins in the ocean, and three times that number joins in from a river which has its mouth at the ocean, calculate the total number of dolphins in the ocean. Let's answer step by step:
When three times the number of dolphins in the ocean joins in from a river, the number of dolphins in the ocean increases by 3 * 65 = 195. The total number of dolphins in the ocean increases to 195 + 65 = 260. The answer: 260.