The document appears to be a worksheet with arithmetic problems. Below are the calculations for each of the problems provided:

### Bài 2. Tính
1. 22.3 − 4
\[ 22.3 - 4 = 18.3 \]

2. 16 − 23.2
\[ 16 - 23.2 = -7.2 \]

3. 4² − 4.2
\[ 4^2 - 4.2 = 16 - 4.2 = 11.8 \]

4. 3³ − 2.3²
\[ 3^3 - 2 \cdot 3^2 = 27 - 2 \cdot 9 = 27 - 18 = 9 \]

5. 72 − 9.22
\[ 72 - 9 \cdot 22 = 72 - 198 = -126 \]

6. 22.3 + 4²
\[ 22.3 + 4^2 = 22.3 + 16 = 38.3 \]

7. 42.3 + 22.4
\[ 42.3 + 22.4 = 64.7 \]

8. 22.3 + 16 : 8
\[ 22.3 + \frac{16}{8} = 22.3 + 2 = 24.3 \]

9. 42 : 2 + 32.2
\[ \frac{42}{2} + 32 \cdot 2 = 21 + 64 = 85 \]

10. 62 : 2 − 3².2
\[ \frac{62}{2} - 3^2 \cdot 2 = 31 - 9 \cdot 2 = 31 - 18 = 13 \]

11. 32 : 4² + 42 : 7
\[ \frac{32}{4^2} + \frac{42}{7} = \frac{32}{16} + 6 = 2 + 6 = 8 \]

12. 16 : 22 + 23.3 − 32
\[ \frac{16}{22} + 23 \cdot 3 - 32 = \frac{8}{11} + 69 - 32 \approx 0.727 + 69 - 32 = 37.727 \]

### Bài 3. Tính:
1. 13 + 21.5 - (198:11 - 8)
\[ 13 + 21.5 - \left(\frac{198}{11} - 8\right) = 13 + 21.5 - (18 - 8) = 13 + 21.5 - 10 = 24.5 \]

2. 272: 16 − 5 + 4(30 − 5 − 255:17)
\[ \frac{272}{16} - 5 + 4(30 - 5 - \frac{255}{17}) = 17 - 5 + 4 \left(30 - 5 - 15 \right) = 17 - 5 + 4(10) = 17 - 5 + 40 = 52 \]

3. 15.24 − 14.5 (145:5−27)
\[ 15.24 - 14.5\left(\frac{145}{5} - 27\right) = 15.24 - 14.5(29 - 27) = 15.24 - 14.5(2) = 15.24 - 29 = -13.76 \]

4. 18.3 − 18.2 + 3(51:17)
\[ 18.3 - 18.2 + 3\left(\frac{51}{17}\right) = 18.3 - 18.2 + 3(3) = 0.1 + 9 = 9.1 \]

5. (64 + 115 + 36) − 25.8
\[ 64 + 115 + 36 - 25.8 = 215 - 25.8 = 189.2 \]

6. 15.8 − (17 − 30 + 83) − 144:6
\[ 15.8 - (17 - 30 + 83) - \frac{144}{6} = 15.8 - (70) - 24 = 15.8 - 70 - 24 = -54.2 \]

7. 250:50 − (46 − 75 + 54):5
\[ \frac{250}{50} - \frac{46 - 75 + 54}{5} = 5 - \frac{25}{5} = 5 - 5 = 0 \]

8. 13(17 − 95 + 83):5 − 18:9
\[ 13(17 - 95 + 83) : 5 - \frac{18}{9} = 13(5) : 5 - 2 = 65 : 5 - 2 = 13 - 2 = 11 \]

9. 140 − 180 (47 − 90 + 43) + 7
\[ 140 - 180(47 - 90 + 43) + 7 = 140 - 180(0) + 7 = 140 + 7 = 147 \]

10. 24 (15 + 30 + 85 − 120):10
\[ 24(15 + 30 + 85 - 120):10 = 24(10):10 = 240 : 10 = 24 \]

11. 27 + 73 − 30:(25−10)
\[ 27 + 73 - \frac{30}{25 - 10} = 27 + 73 - 2 = 98 \]

12. 18 − 4 (27 − 90 + 73):10²
\[ 18 - 4(27 - 90 + 73):10^2 = 18 - 4(10):100 = 18 - \frac{40}{100} = 18 - 0.4 = 17.6 \]

These calculations should help solve the arithmetic problems given.