Explanation:

Following the pattern as shown in the series we will get 296 as the answer

5× 2−2=8
8× 2+4=20
20× 2−6=34
34× 2+8=76
76× 2−10=142
142× 2+12=296

Each number is multiplied by 2 and then firstly it is subtracted by 2 then multiple of 2 which is 4 is added to the other number then in the preceding number same pattern is followed.