5x-2 (20x) =79

x = 17

So she made a mistake. 20- 17=3.

2. Solution: Suppose Yuanyuan's home is about X kilometers (x>3) away from Grandma's home, then

10+1.8 (x-3) =13.6 (10 yuan is 3km).

x =5

So it's about five kilometers.

3. Solution: Suppose that the original A heap has X blocks, and then the B heap has 2x blocks, then

x+9=2x-9

x= 18

So there are 18 pieces in the armor pile.

There is no data for this problem, so it is difficult to calculate.

5. solution: if the nickname is right for question x, then it is wrong for question (20-x), then

5x-3 (20x) =60

x= 15

So the nickname is right, 15.

Correct rate: 40 ÷ (10+40) = 80%.

Two. 1.45+ 15× 6 = 135

2.250÷5×8= 400

3.6×5÷2×4= 60

4.30×3+8= 98

5.400÷4+20×5= 300

6. 10+ 12÷3+20= 34

7.(80÷20+80)÷4= 2 1

8.70+( 100- 10×5)= 120

9.360÷40= 9

10.40×20= 800

1 1.80-25= 55

12.70+45= 1 15

13.90×2= 180

14. 16×6= 96

15.300×6= 1800

16.540÷9= 60

17.30×20= 600

18.400÷4= 100

19.350-80= 270

20. 160+70= 230

2 1. 18-64÷8= 10

22.42÷6+20= 27

23.40-5×7= 5

24.80+60÷3= 100

25.4 1+ 18÷2= 50

26.75- 1 1×5= 20

27.42+7-29= 20

28.5600÷80= 70

29.25× 16= 400

30. 120×25= 3000

3 1.36× 1 1= 396

32. 1025÷25= 4 1

33.336+70= 406

34.25×9×4= 900

35.200-33×3= 10 1

36.3020- 10 10= 20 10

37. 12×50= 600

38.25×8= 200

39.23× 1 1= 253

40. 125÷25= 5

4 1.4200-2200=2000

42.220+80= 300

43.20×8×5= 800

44.600-3×200= 0

45.20+20÷2= 30

46.35-25÷5= 30

47.36+8-40= 4

48.2800÷40= 70

49.98÷ 14 = 7

50.96÷24 = 4

5 1.56÷ 14 = 4

52.65÷ 13 = 5

53.75÷ 15 = 5

54. 120÷24 = 5

55.200÷25 = 8

56.800÷ 16 = 50

57.840÷2 1 = 40

58.560÷ 14 = 40

59.390÷ 13 = 30

60.600÷ 15 = 40

6 1.72÷24 = 3

62.85÷ 17 = 5

63.90÷ 15 = 6

64.96÷ 16 = 6

65.78÷26 = 3

66.5 1÷ 17 = 3

67.80÷40 = 2

68. 100÷20 = 5

69. 100÷4 = 25

70.240÷40 = 6

7 1.920÷4 = 230

72.300÷60= 5

73.64÷2 = 32

74.64÷4 = 16

75.50÷5 = 10

76.60÷8 = 7.5

77.96÷4 = 24

78.90÷6 = 15

79.400+80 = 480

80.400-80 = 320

8 1.40×80 = 3200

82.400÷80 = 5

83.48÷ 16 = 3

84.96÷24 = 4

85. 160×5= 800

86.4×250= 1000

87.0×5 18= 0

88. 10×76= 760

89.36× 10= 360

90. 15×6= 90

9 1.24×3= 72

92.5× 18= 90

93.26×4= 104

94.7× 15= 105

95.32×30= 960

96.40× 15= 600

97.60× 12= 720

98.23×30= 690

99.30×50= 1500

100.5×700=3500

Believe me, it must be right! ! ! ! ! !