| 1. | 4 + 5 = + 4 | |
| 2. | 8 + 6 = + 8 | |
| 3. | + 3 = 3 + 7 | |
| 4. | (4 + 3) + 6 = 4 + ( + 6) | |
| 5. | 9 + (4 + 2) = ( + 4) + 2 | |
| 6. | (5 + ) + 7 = 7 + (3 + 5) | |
| 7. | 3 + 7 = | |
| 8. | 8 + 6 = | |
| 9. | 4 + 9 = | |
| 10. | 6 + 5 = | |
| 11. | 9 + 7 = | |
| 12. | 6 + 7 = | |
| 13. | 8 + 2 + 5 = | |
| 14. | 4 + 7 + 3 = | |
| 15. | 6 + 5 + 5 = | |
| 16. | 8 + 9 + 1 = | |
| 17. | 6 + 4 + 7 = | |
| 18. | 5 + 3 + 5 = | |