Solution,
P={7,8,12,19}
Q={12,15,17,19}
P U Q={7,8,12,19} U { 12,15,17,19}
={ 7,8,12,15,17,19}
P-Q={7,8,12,19}-{12,15,17,19}
={7,8}
Hope it helps
Good luck on your assignment
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