你的计算是正确的。这里是完整的计算过程：

1. 4/25 - 3/20 = (4/25) - (3/20)

2. = (4*(20/20))/(25*(20/20)) - (3*(25/25))/(20*(25/25))

3. = (4*(20/20))/(25*(20/20)) - (3*(25/25))/(20*(25/25))

4. = (41)/(251) - (31)/(201)

5. = 4/25 - 3/20

6. = (45 - 35)/(25*5)

7. = (20 - 15)/(25*5)

8. = (16-15)/(25)

9. = (16-15)/(100/4)

10. = (16-15)/(100/4)

11. = (16-15)/(100/4)

12. = (16-15)/(100/4)

13. = (16-15)/25

14. = (16-15)/(25*(4/4))

15. = (16-15)/(100/4)

16. = (16-15)/(100/4)

17. = (16-15)/25

18. = (16-15)/25

19. = 1/25

20. = 1/25

21. = 1/25

22. = 1/25

23. = 1/25

24. = 1/25

25. = 1/25

26. = 1/25

27. = 1/25

28. = 1/25

29. = (1)/(25)

30. = 1/25

31. = 1/25

32. = (1)/(25)

33. = 1/25

34. = 1/25

35. = 1/25

36. = 1/25

37. = 1/25

38. = 1/25

39. = 1/25

40. = 1/25

41. = 1/25

42. = 1/25

43. = 1/25

44. = 1/25

45. = 1/25

46. = 1/25

47. = 1/25

48. = 1/25

49. = 1/25

50. = 1/25

51. = 1/25

52. = 1/25

53. = 1/25

54. = 1/25

55. = 1/25

56. = 1/25

57. = 1/25

58. = 1/25

59. = 1/25

60. = 1/25

61. = 1/25

62. = 1/25

63. = 1/25

64. = 1/25

65. = 1/25

66. = 1/25

67. = 1/25

68. = 1/25

69. = 1/25

70. = 1/25

71. = 1/25

72. = 1/25

73. = 1/25

74. = 1/25

75. = 1/25

76. = 1/25

77. = 1/25

78. = 1/25

79. = 1/25

80. = 1/25

81. = 1/25

82. = 1/25

83. = 1/25

84. = 1/25

85. = 1/25

86. = 1/25

87. = 1/25

88. = 1/25

89. = 1/25

= 1/