7 people average age is 30 . youngest person age is 5 . find average of the people when youngest was born .
average age of people = 30 so have total age = 210 before 7 years we have to deduct each person age by seven years 210 - 35 = 161 so average age would be 175 / 7 = 25 answer : c
divide(subtract(multiply(30, 7), multiply(5, 7)), 7)