The answer is 36.
-19+17 = -2
36
16 + 16 + 16 + 17 + 18 + 18 + 18 + 19 + 19 + 20 + 20 + 20 + 21 = 238
64It is the same as 17+28+19 = 64
17 + 19 = 36
The answer is 672.
1 + 18 = 19, 2 + 17 = 19, etc. 10 + 9 = 21 correct
-36
17 + 8 + 5 + 19 = 49
17 + 14 + 17 + 19 + 18 + 13 + 11 = 109
2 + 17 = 19
17 + 2 = 19
-2
491
16 + 16 + 16 + 17 + 18 + 18 + 18 + 19 + 19 + 20 + 20 + 20 + 21 = 238
64It is the same as 17+28+19 = 64
How about 2 plus 17 = 19 as one example
17 + 19 = 36
3 + 11 + 11 + 11 + 12 + 13 + 15 + 15 + 16 + 17 + 19 = 143