Find the next two terms of each sequence

15, 7,-1, -9

2 answers

keep subtracting 8
7 - 15 = - 8

- 1 - 7 = - 8

- 9 - ( - 1 ) = - 9 + 1 = - 8

This is an arithmetic progression with common difference d = - 8

Next two term:

- 9 - 8 = - 17

- 17 - 18 = - 25