Answer: 20
Explanation:
We will find a pattern within these numbers. Let x be the missing numbers. You can see that there is a pattern in the subtraction, with each term being distracted with n (1st and 2nd term by 1, 2nd and 3rd term by 2, etc).
15 - 14 = 1
17 - 15 = 2
x - 17 = 3
24 - x = 4
29 - 24 = 5
Then, we can solve one of these equations for x.
x - 17 = 3
x = 20