It can be seen that sets A and B are points on functions, and A∩B is the intersection of two functions. We can draw a picture and know that two functions have two intersections.
So the set A∩B contains two elements. According to a set of formulas in which n elements * * * have 2 n subsets, where a * * * has 2? =4 subsets.
Off-topic: If the topic asks you to write A∩B, you can use simultaneous binary function equation to calculate.