Răspuns:
1a. A={14, 15, 16, 17, 18, 19 , 20}
B= { 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
AUB={ 3, 4 , 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 , 20}
AnB= { 14,15}
A-B={16, 17, 18, 19 , 20}
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