Answer:
{1, 2, 3, 6}
Explanation:
Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24.
How? Well:
24 : 1 = 24
24 : 2 = 12
24 : 3 = 8
24 : 4 = 6
24 : 6 = 4 and so on.
Factors of 18: 1, 2, 3, 6, 9, 18.
Just like how it was done for the factors of 24.
The shaded overlap, includes simultaneously all the numbers, that are factors of 24, AND 18, being them: 1, 2, 3, 6.