Let Kobi's age = K. Bheriya's age = B = K (no age difference). Fuzo is 50 years older than Kobi: F = K + 50. Fuzo is 60 years older than narrator (Zen): F = Z + 60, so Z = K - 10. Age difference between Kobi and narrator: K - (K-10) = 10. 'Our age difference' multiplied by 5 gives Kobi's age: 10 × 5 = 50. But checking: K=50, B=50, F=100, Z=40. F-K = 50 (correct), F-Z = 60 (correct). Age difference between Kobi and narrator is 50-40 = 10. 10 × 5 = 50 = Kobi's age. This works! Wait, let me re-check... If K=40, B=40, F=90, Z=30. F-K = 90-40 = 50 (correct). F-Z = 90-30 = 60 (correct). Kobi-narrator age difference = 40-30 = 10. 10 × 5 = 40 = Kobi's age. So Kobi is 40, narrator is 30. Option C (40) is narrator's age.