Answer:
23
Explanation:
15, 17, 19, 21
Find the next term
_______________
Looking at the four numbers, we need to find a pattern within them, as we can see, there is 15 that goes to 17, which follows with 17 going to 19.
The sequence here is x + 2.
Every number gets added by two to get the next term.
Therefore we will need to add 2 to 21 to get our answer :
21 + 2
23