c)Two departments of size ten ({a1,...,a10} and {b1,...,b10} choose two members to participate in a committee ai, aj, bi and bj . The committee has a chair, but no other members ranked. How many unique committees exist? (e.g. Chair: a2, Members: a3, b2, b9 is an example)

d) Consider the following equation x1 + x2 +x3 = 20. Let xi = max(x1,x2,x3). What is the minimum value for xi?