Fill in the blanks with the correct number.
1. 4 + 8 = 9 + ___
2. 8 + 4 = 2 + ___
3. 7 + 3 = 1 + ___
4. 10 + 10 = 20 + ___
5. 4 + ___ = 10 + 6
6. 2 + ___ = 3 + 5
7. 8 + 3 = 10 + ___
8. 5 + 6 = 1 + ___
9. 4 + 10 = 9 + ___
10. 9 + 9 = 8 + ___
11. 1 + ___ = 7 + 7
12. 18 + ___ = 10 + 10
13. ___ + 5 = 10 + 0
14. 2 + 9 = ___ + 7
15. 17 + 3 = 16 + ___
16. 16 + 4 = 17 + ___