- 200
- 280
- 320
- 420
- c
-
20,40,80,160,_____
20+20=40
40+40=80
80+80=160
160+160=320
320+320=640
20,40,80,160,_____
20+20=40
40+40=80
80+80=160
160+160=320
320+320=640