2.
Find the next term.
15, 17, 19, 21, ...
19
25
23
42

23

Step-by-step 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