mathematics
posted by Iby .
the average age of a family of six is 25 years.The average age of the four children is 15 years.If the father is 2 years older than the mother,calculate the age of the mother.

The sum of the ages of the six family members is 150. You get that from the average and the fact that there are six of them. The sum of the ages of the four children is 60.
Let x be the mother's age. The father's age is x+2.
You know that 60 + x + x + 2 = 160
Solve for x. 
the sum of the four family members is 88,after the child was adopted then is 120.
the age at which the child was adopted is totalage (120) the age that he was adopted after (2)
=30 years
...the child was adopted at 30 years 
the sum of the four family members is 88,after the child was adopted then is 120.
the age at which the child was adopted is total age (120) the age of the other 4 members (88)
=32 years
then we minus the 2 yrs that he was adopted after(302)
=the child was adopted at 30 years