A man was 31 years of age when he had his first son. His wife was 26 years of age when his son attained the age of 7 years. The difference in age between the man and his wife is :

Age of man at the birth of first son = 31 years
The age of wife at the birth of her son = 26 – 7 = 19 years
Required difference = Age of man at the birth of first son - The age of wife at the birth of her son
Required difference = ( 31 – 19 ) years = 12 years