Answer:
19
Explanation
This is simple
I will teach you a simple technique
Count them, don't count the -8
-8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
You are just subtracting, but instead counting.
I said not to count -8, because normally in subtraction, we normally don't count the number we are subracting.
for example
8 - 7 = 1
so counting technique
8 - 7, 6, 5, 4, 3, 2, 1
there are 7 numbers, if i didn't count the 8
so it is right.
hope you understand :-)