The answer is:
20, 24, 28
Work/explanation:
To find the pattern, we should find the amount that is added or subtracted each time, to arrive at the next term; this amount is known as the common difference.
In our case, we add 4 each time : 4, 8, 12, 16...
To find the next three terms, we add 4 again:
16 + 4 = 20
Repeat this step two more times:
20 + 4 = 24
24 + 4 = 28
Hence, the next three terms are 20, 24, and 28.