So there are 20 people in the family. The total cost of the tickets were $100. Tickets for adults cost $8 and children cost $4. To find the answer for the number of adults you need to divide the $100 by $8 and do the same for children but divide the $100 by $4. So 5 of the family members were adults and 15 were children. 5 adults = $40 15 children = $ 60