425. Выполните вычитание: 1) 1/3 − 1/9; 2) 10/21 − 1/3; 3) 14/15 − 3/5; 4) 17/18 − 1/9; 5) 4/9 − 13/45; 6) 1/3 − 7/30.

1. \(\frac{1}{3}-\frac{1}{9}=\frac{3}{9}-\frac{1}{9}=\frac{2}{9}\).
2. \(\frac{10}{21}-\frac{1}{3}=\frac{10}{21}-\frac{7}{21}=\frac{3}{21}=\frac{1}{7}\).
3. \(\frac{14}{15}-\frac{3}{5}=\frac{14}{15}-\frac{9}{15}=\frac{5}{15}=\frac{1}{3}\).
4. \(\frac{17}{18}-\frac{1}{9}=\frac{17}{18}-\frac{2}{18}=\frac{15}{18}=\frac{5}{6}\).
5. \(\frac{4}{9}-\frac{13}{45}=\frac{20}{45}-\frac{13}{45}=\frac{7}{45}\).
6. \(\frac{1}{3}-\frac{7}{30}=\frac{10}{30}-\frac{7}{30}=\frac{3}{30}=\frac{1}{10}\).

Ответ: 1) 2/9; 2) 1/7; 3) 1/3; 4) 5/6; 5) 7/45; 6) 1/10.