Question

Which numbers in Set A = (-7, 4, 2, 14, 21, 34, 42) are elements of both Set B and Set C, shown below?

Answer 1

Greetings from Brasil...

Rewriting the problem sets

A = {-7, 4, 2, 14, 21, 34, 42}

B = {...; 2; 4; 6; 8; 10; 12; 14; 16; 18; 20; 22; 24; 26; 28; 30; 32; 34; 36; 38; 40; 42;...}

C = {...; -14; -7; 0; 7; 14; 21; 28; 35; 42; 49; 56; 63; 70; 77;...}

So, according to the statement, it is desired:

A ∩ B ∩ C - the intersection between the 3 sets, that is, which numbers are present simultaneously in the 3 sets....

Looking at the sets we conclude that

A ∩ B ∩ C = {14; 42}