回答如下：1. 45 + 27 - 13 = 59
2. 68 - 23 + 15 = 60
3. 96 - 12 - 23 = 61
4. 85 + 27 - 49 = 63
5. 64 - 27 + 18 = 55
6. 92 - 35 + 14 = 71
7. 78 + 24 - 39 = 63
8. 56 - 15 + 27 = 68
9. 74 - 29 - 17 = 28
10. 83 + 18 - 39 = 62
11. 47 - 18 + 24 = 53
12. 69 + 15 - 27 = 57
13. 52 - 19 + 27 = 60
14. 63 + 21 - 38 = 46
15. 87 - 36 + 14 = 65
16. 76 - 29 - 17 = 30
17. 91 + 15 - 38 = 68
18. 58 - 17 + 23 = 64
19. 72 + 27 - 45 = 54
20. 85 - 18 + 37 = 104。
