Answer: i forgot what the sequence is called but it is that sequence where you where subtract the first two numbers so for example if you subtract 13 from 23 you would get ten then you go to the next set of numbers so then you would subtract 33 from 43 and get 10..
Explanation:
23-13=10, 43-33=10, 53-43=10, 63-53=10 and so on
so this sequence is having you find the common difference
hope this helps