Respuesta :

Answer:

Step-by-step explanation:

I think the question is  card(A)=20,card(B)=15,card(A∩B)=10, then what iscard(A∪B)  

You can solve this question by drawing a picture like this to visualize the problem.

Thus the answer is  card(A∪B)=card(A)+card(B)−card(A∩B)=25

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