№1. Вычислите: а) 3/8 + 1/16; б) 7/15 − 13/25; в) −13/16 · 20/39; г) 15/21 : 12/35; д) 2 7/18 + 5 13/24; е) 4 5/18 − 2 5/9; ж) 3 3/25 · 4; з) 8 1/6 : 7.

1. а) \(\frac{3}{8}+\frac{1}{16}=\frac{6}{16}+\frac{1}{16}=\frac{7}{16}\).
2. б) \(\frac{7}{15}-\frac{13}{25}=\frac{35}{75}-\frac{39}{75}=-\frac{4}{75}\).
3. в) \(-\frac{13}{16}\cdot\frac{20}{39}=-\frac{1}{4}\cdot\frac{5}{3}=-\frac{5}{12}\).
4. г) \(\frac{15}{21}:\frac{12}{35}=\frac{5}{7}\cdot\frac{35}{12}=\frac{25}{12}=2\frac{1}{12}\).
5. д) \(2\frac{7}{18}+5\frac{13}{24}=7+\frac{28}{72}+\frac{39}{72}=7\frac{67}{72}\).
6. е) \(4\frac{5}{18}-2\frac{5}{9}=4\frac{5}{18}-2\frac{10}{18}=2-\frac{5}{18}=1\frac{13}{18}\).
7. ж) \(3\frac{3}{25}\cdot4=\frac{78}{25}\cdot4=\frac{312}{25}=12\frac{12}{25}\).
8. з) \(8\frac{1}{6}:7=\frac{49}{6}:7=\frac{49}{6}\cdot\frac{1}{7}=\frac{7}{6}=1\frac{1}{6}\).

Ответ: а) \(\frac{7}{16}\); б) \(-\frac{4}{75}\); в) \(-\frac{5}{12}\); г) \(2\frac{1}{12}\); д) \(7\frac{67}{72}\); е) \(1\frac{13}{18}\); ж) \(12\frac{12}{25}\); з) \(1\frac{1}{6}\).