The average age of a husband and wife at the time of their marriage was 25 years. A son was born to them two years after their marriage. The present average age of all three of them is 24 years. How many years is it since the couple got married?

Sum of the ages of husband and wife at the time of their marriage
= (25 × 2) yrs
= 50 yrs
Sum of the ages of husband and wife when their son was born
= (50 + 2 × 2) yrs
= 54 yrs
Sum of the ages of husband, wife and son at present
= (24 × 3) yrs
= 72 yrs
∴ Age of son = $$\frac{{\left( {72 - 54} \right)}}{3}$$   = $$\frac{{18}}{3}$$   = 6 years
Hence, the couple got married (6 + 2) = 8 years ago