Answer:
1. 20
2. 16
3. 50
4. 0
5. 12
6. -12
7. 45
8. 99
9. 54
10. 49
You're suppose to do the opposite of each problem. So since it's division, you would multiple. (Example: x/4=2 (4 x 2=8) (x=8) (8/4=2<---- answer proven)