1. Выполните сложение: а) 4/5 + 3/7; б) 5/12 + 9/20; в) 5/18 + 4/45; г) 12/17 + 27/34.

1. \(\frac{4}{5}+\frac{3}{7}=\frac{28}{35}+\frac{15}{35}=\frac{43}{35}=1\frac{8}{35}\).
2. \(\frac{5}{12}+\frac{9}{20}=\frac{25}{60}+\frac{27}{60}=\frac{52}{60}=\frac{13}{15}\).
3. \(\frac{5}{18}+\frac{4}{45}=\frac{25}{90}+\frac{8}{90}=\frac{33}{90}=\frac{11}{30}\).
4. \(\frac{12}{17}+\frac{27}{34}=\frac{24}{34}+\frac{27}{34}=\frac{51}{34}=1\frac{17}{34}\).

Ответ: а) \(1\frac{8}{35}\); б) \(\frac{13}{15}\); в) \(\frac{11}{30}\); г) \(1\frac{17}{34}\).