7 people average age is 30 . youngest person age is 6 . 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 - 42 = 161 so average age would be 161 / 7 = 24 answer : b"
divide(subtract(multiply(30, 7), multiply(6, 7)), 7)