The average age of the mother and her 6 children is 12 years which is reduced by 5 years if the mother is excluded. How old is the mother?

Average age of mother and 6 children = 12 years

Total age of mother and 6 children = 12 X 7 = 84 years

When the mother's age is excluded, average of 6 children = 12 - 5 = 7

Total age of 6 children = 7 X 6= 42 years

Hence mother's age = 84 - 42 = 42 years