Solve the math problem.
19
- 0
15
- 5
- 2
7 - 5 =
- 6
13 - 7 =
18
- 1
17 - 4 =
16
20
17 - 6 =
9
- 7
14
8 - 2 =
12 - 3 =
11
- 9
18 - 9 =
8 - 8 =
4 - 2 =
17 - 2 =
12 - 5 =
6 - 6 =
8