In a family, there are four members: a father, a mother, a son, and a daughter. The father is older than the mother, the mother is older than the son, and the son is older than the daughter. Who is the youngest in the family?
A store sells pencils for $0.50 each and erasers for $0.75 each. If a student buys a total of 10 items for $6.00, how many pencils did the student buy?