54
11 12 15 16 18 17 the answer is 15.5
12 11 18 14 24 17 30 20.. i think ;-) pattern: 18-12 = 6 14-11 = 3 24-18 = 6 17-14 = 3 i hope that helps.
1 + 17 = 18 5 + 13 = 18 7 + 11 = 18
-20, -17, -12, -11, 6, 7, 8, 10, 11, 16, 17, 18, 20
18 + 12 = 30
30
18+11 = 29
The sum of 11 and 7 is 18.
18 can be made in the following ways: 1+17 2+16 3+15 4+14 5+13 6+12 7+11 8+10 9+9
17 + 1 = 18
23
11