Question: 1. Does there exist a planar graph with five vertices, ten edges, and seven faces?
2. Prove that 
3. Decrypt the message yzmzmz hofth wl mlg gzhgv orpv yzmzmzh, which was encrypted using the atbash cipher.
4. A basket contains ten numbered balls; seven are purple and three are teal. You pull four balls out of the basket.
(a) How many different sets of four balls could you pull out of the basket?
(b) How many sets of four balls are all purple?
(c) How many sets of four balls contain at least one teal ball?