The sum of age of two daughters an 1 son =45 yrs
then father's age will be =45 yrs
after 15 yrs, the sum of two daughters and 1 son=45 yrs+ 45 yrs= 90 yrs
after 15 yrs , the father age will be = 60 yrs
the sum of ages of his children are 1 and half times of their father's age