Dưới đây là lời giải cho các phương trình từ câu 13 đến câu 36:

### Giải phương trình

**13)** \( 2x - \frac{1}{2} = -5 \)
- \( 2x = -5 + \frac{1}{2} \)
- \( 2x = -\frac{10}{2} + \frac{1}{2} = -\frac{9}{2} \)
- \( x = -\frac{9}{4} \)

**14)** \( 2x - \frac{1}{3} = -\frac{4}{9} \)
- \( 2x = -\frac{4}{9} + \frac{1}{3} = -\frac{4}{9} + \frac{3}{9} = -\frac{1}{9} \)
- \( x = -\frac{1}{18} \)

**15)** \( 3x - \frac{3}{5} = -7 \)
- \( 3x = -7 + \frac{3}{5} = -\frac{35}{5} + \frac{3}{5} = -\frac{32}{5} \)
- \( x = -\frac{32}{15} \)

**16)** \( \frac{1}{2} + \frac{2}{3}x = \frac{4}{5} \)
- \( \frac{2}{3}x = \frac{4}{5} - \frac{1}{2} = \frac{8}{10} - \frac{5}{10} = \frac{3}{10} \)
- \( x = \frac{3}{10} \times \frac{3}{2} = \frac{9}{20} \)

**17)** \( \frac{3}{4} + \frac{5}{2}x = 7 \)
- \( \frac{5}{2}x = 7 - \frac{3}{4} = 7 - \frac{3}{4} \)
- \( \frac{5}{2}x = \frac{28}{4} - \frac{3}{4} = \frac{25}{4} \)
- \( x = \frac{25}{4} \times \frac{2}{5} = \frac{25}{10} = \frac{5}{2} \)

**18)** \( \frac{5}{7}x - \frac{2}{3} = \frac{3}{10} \)
- \( \frac{5}{7}x = \frac{3}{10} + \frac{2}{3} \)
- Tìm mẫu số chung = 30:
- \( = \frac{9}{30} + \frac{20}{30} = \frac{29}{30} \)
- \( x = \frac{29}{30} \times \frac{7}{5} = \frac{29 \times 7}{150} = \frac{203}{150} \)

**19)** \( \frac{3}{4} + x = -5 \)
- \( x = -5 - \frac{3}{4} = -\frac{20}{4} - \frac{3}{4} = -\frac{23}{4} \)

**20)** \( \frac{4}{5} + x = -\frac{1}{2} \)
- \( x = -\frac{1}{2} - \frac{4}{5} = -\frac{5}{10} - \frac{8}{10} = -\frac{13}{10} \)

**21)** \( \frac{3}{5}x = \frac{2}{7} \)
- \( x = \frac{2}{7} \times \frac{5}{3} = \frac{10}{21} \)

**22)** \( \frac{5}{2} - \frac{2}{3}x = 1 \)
- \( -\frac{2}{3}x = 1 - \frac{5}{2} = -\frac{3}{2} \)
- \( x = -\frac{3}{2} \times -\frac{3}{2} = \frac{9}{4} \)

**23)** \( \frac{2}{3}x - \frac{4}{5} = -\frac{1}{2} \)
- \( \frac{2}{3}x = -\frac{1}{2} + \frac{4}{5} = -\frac{5}{10} + \frac{8}{10} = \frac{3}{10} \)
- \( x = \frac{3}{10} \times \frac{3}{2} = \frac{9}{20} \)

**24)** \( \frac{4}{5} + \frac{1}{3}x = -1 \)
- \( \frac{1}{3}x = -1 - \frac{4}{5} = -\frac{5}{5} - \frac{4}{5} = -\frac{9}{5} \)
- \( x = -\frac{9}{5} \times 3 = -\frac{27}{5} \)

**25)** \( \frac{2}{1} - \frac{5}{3}x = 1 \)
- \( -\frac{5}{3}x = 1 - 2 = -1 \)
- \( x = -1 \times -\frac{3}{5} = \frac{3}{5} \)

**26)** \( \frac{4}{5}x + 2 = 2 \)
- \( \frac{4}{5}x = 0 \)
- \( x = 0 \)

**27)** \( \frac{2}{3}x + 2 = \frac{5}{5} \)
- \( \frac{2}{3}x = \frac{5}{5} - 2 = \frac{5}{5} - \frac{10}{5} = -\frac{5}{5} \)
- \( x = -\frac{5}{5} \times \frac{3}{2} = -\frac{15}{10} = -\frac{3}{2} \)

**28)** \( \frac{3}{4}x - \frac{1}{3} = -1 \)
- \( \frac{3}{4}x = -1 + \frac{1}{3} = -\frac{3}{3} + \frac{1}{3} = -\frac{2}{3} \)
- \( x = -\frac{2}{3} \times \frac{4}{3} = -\frac{8}{9} \)

**29)** \( \frac{5}{4}x = 2 \)
- \( x = 2 \times \frac{4}{5} = \frac{8}{5} \)

**30)** \( \frac{2}{3}x = \frac{3}{4} \)
- \( x = \frac{3}{4} \times \frac{3}{2} = \frac{9}{8} \)

**31)** \( \frac{1}{7} + \frac{3}{7}x = \frac{3}{14} \)
- \( \frac{3}{7}x = \frac{3}{14} - \frac{1}{7} = \frac{3}{14} - \frac{2}{14} = \frac{1}{14} \)
- \( x = \frac{1}{14} \times \frac{7}{3} = \frac{1}{6} \)

**32)** \( \frac{11}{5} + x = \frac{3}{4} \)
- \( x = \frac{3}{4} - \frac{11}{5} \)
- \( = \frac{15}{20} - \frac{44}{20} = -\frac{29}{20} \)

**33)** \( \frac{1}{2} + \frac{1}{3}x = -1 \)
- \( \frac{1}{3}x = -1 - \frac{1}{2} = -\frac{3}{2} \)
- \( x = -\frac{3}{2} \times 3 = -\frac{9}{2} \)

**34)** \( \frac{3}{4} + \frac{1}{6}x = 2 \)
- \( \frac{1}{6}x = 2 - \frac{3}{4} = \frac{8}{4} - \frac{3}{4} = \frac{5}{4} \)
- \( x = \frac{5}{4} \times 6 = \frac{30}{4} = \frac{15}{2} \)

**35)** \( -\frac{5}{6} + x = 2 \)
- \( x = 2 + \frac{5}{6} = \frac{12}{6} + \frac{5}{6} = \frac{17}{6} \)

**36)** \( -\frac{1}{4} + \frac{3}{6}x = \frac{11}{36} \)
- \( \frac{3}{6}x = \frac{11}{36} + \frac{9}{36} = \frac{20}{36} \)
- \( x = \frac{20}{36} \times \frac{6}{3} = \frac{40}{36} = \frac{10}{9} \)

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