The author of this website has a book called Game Theory 101 which is a really good aide or a compliment to someone learning Game Theory who wants a clear, concise, and simple to understand introduction to solving games in game theory. Its rather surprising how many Game Theory books just assume the reader understands how to solve the Games they are discussing without actually running through literal examples. The authors book is pretty good but he also has a large number of videos up on his website and youtube were he provides additional insight and solutions. Here is a video on calculating payoffs in mixed strategy nash equilibrium. Fun stuff.