The difference between Rajiv's and Raghu's ages is a constant 8 years, so when their ratio is 5 : 7, the difference of 2 parts equals 8 years, making each part 4 years. This means their current ages are 5 times 4 equal to 20 years and 7 times 4 equal to 28 years, summing to 48 years. Since the father is currently 50 years old and the sum of the sons' ages is 48, the father is 2 years older than the sum of their ages. When the ratio of the sons' ages becomes 2 : 3, the difference of 1 part equals 8 years, meaning their ages will be 16 and 24, which sum to 40. Therefore, the father's age will be 40 plus 2, which is 46 years.