rank | 1st | 2nd |TOTAL
------|-----+-------|----------
a | 6 + 9 | =15
b | 7 + 3 | =16
c | 9 + 7 | =23
d | 6 + 7 | =22
e | 8 + 1 | =?
If you add the 1st in line a (6) and you add it to the 1st in line b (7) + the 2nd in line b (3) you get 16. Repeat the same logic/pattern to all c,d..
This is the pattern to all this puzzle;
So the before last term is : 9+6+7 = 22
and the last term : 6+8+1 = 15
