A = {multiples of 5 between 14 and 26}. B = {odd numbers between 14 and 26}. List the members of A∪B and A∩B.

First write down explicitly what the elements of A and B are.A={15,20,25}, B={15,17,19,21,23,25}.
Remember ∪ means OR. So A ∪ B is the set of items which are in either A OR B. This is {15,17,19,21,23,25,15,20,25}.
Remember ∩ means AND. So A ∩ B is the set of items which are in both A AND B. This is {15,25}.