Answer: 24
Step-by-step explanation:
Basically you just need to add the sides up to get your answer, its like breaking it up and adding simply.
x | y
——-
-10|-18
-9 |-17
-8 |-16
-7 |-15
-6 |-14
-5 |-13
-4 |-12
-3 |-11
-2|-10
-1 | -9
0 | -8
1 | -7
2 |-6
3 | -5
4 | -4
5 | -3
6 | -2
7 | -1
8 | 0
9 | 1
10| 2
109-91 is 18, but multiplied is 9919