SSC CGL 21-August-2017 Reasoning question 9

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.
-4, ?, 3, 8, 14, 21
Options:
1) 0
2) 1
3) -2
4) -1
Corre ct Answer: -1
Solution:
-4,  (x+4)=3 ,3, 8(3+5), 14(8+6), 21(14+7) => -4, -1, 3, 8, 14, 21