How to find pure strategy Nash equilibrium and mixed Nash strategy?

The simplest method of pure strategic Nash equilibrium is to draw a line. Fix one first, then draw a line under the other, and then fix another income and draw a line under the other. The latter two are connected as pure strategic Nash equilibria, and mixed strategic Nash equilibria need to be calculated, but the sum of the numbers of pure strategic Nash equilibria and mixed strategic Nash equilibria in finite games must be odd. If you get an even number of pure strategic Nash equilibria, there must be another mixed strategic Nash equilibrium.

Nash equilibrium of mixed strategies: G={S 1, ... sn; In u 1, ... un}, mixed strategies combine to form a Nash equilibrium. If for all i= 1, 2 ..., the following formula holds: that is, if a strategy combination makes any player's strategy optimal relative to other players' strategies, then this strategy constitutes a Nash equilibrium, whether it is a mixed strategy or a pure strategy. Nash equilibrium of mixed strategy is a rational strategy facing the uncertainty of other participants' choices. Its main feature is that every pure strategy as a part of mixed strategy has the same expectation. Otherwise, a player will choose the strategy with the highest expectation and exclude all other strategies, which means that the original state is not equilibrium.