Sosthenes is three times as old as Benoni. Five years from now the sum of their ages will be 34 years. What are their present ages?
S = 3B
S + 5 + B + 5 = 34 → S + B + 10 = 34 → S + B = 24 → 3B + B = 24 → 4B = 24 → B = 6 → S = 3B = 18.
Check: (18 + 5) + (6 + 5) = 23 + 11 = 34. Yup.