Question: 1. How many nonnegative solutions are there to the equation w1 + w2 + w3 + w4 = 6?
2. Consider the function f to be defined on the set of finite graphs G and let f(G) = |V(G)|. What is the range of f?
3. Show that any 11 numbers selected from {3,...,30} must include two that have a common divisor (other than 1).