Ответ:

1)

[tex] \frac{1}{5} [/tex]

2)

[tex] \frac{47}{90} [/tex]

3)

[tex] \frac{3}{10} [/tex]

Пошаговое объяснение:

1)

[tex] \frac{7}{15} - \frac{1}{6} - \frac{1}{10} = \\ = \frac{7 \times 10}{15 \times 10} - \frac{1 \times 25}{6 \times 25} - \frac{1 \times 15}{10 \times 15 } = \\ = \frac{70}{150} - \frac{25}{150} - \frac{15}{150} = \\ = \frac{70 - 25 - 15}{150} = \\ = \frac{30}{150} = \frac{30 \times 1}{30 \times 5} = \\ = \frac{1}{5} [/tex]

2)

[tex] \frac{9}{10} - \frac{7}{15} + \frac{4}{45} = \\ = \frac{9 \times 9}{10 \times 9} - \frac{7 \times 6}{15 \times 6} + \frac{4 \times 2}{45 \times 2} = \\ = \frac{81}{90} - \frac{42}{90} + \frac{8}{90} = \\ = \frac{81 - 42 + 8}{90} = \frac{47}{90} [/tex]

3)

[tex] \frac{7}{18} - \frac{1}{5} + \frac{1}{9} = \\ = \frac{7 \times 10}{18 \times 10} - \frac{1 \times 36}{5 \times 36} + \frac{1 \times 20}{9 \times 20} = \\ = \frac{70}{180} - \frac{36 }{180} + \frac{20}{180} = \\ = \frac{70 - 36 + 20}{180} = \\ = \frac{54}{180} = \frac{18 \times 3}{18 \times 10} = \\ = \frac{3}{10} [/tex]