Вычисли: а) \(\frac{2}{3}+\frac{7}{18}\); б) \(\frac{5}{6}+\frac{9}{20}\).

1. \[\frac{2}{3}+\frac{7}{18}=\frac{12}{18}+\frac{7}{18}=\frac{19}{18}=1\frac{1}{18}.\]
2. \[\frac{5}{6}+\frac{9}{20}=\frac{50}{60}+\frac{27}{60}=\frac{77}{60}=1\frac{17}{60}.\]

Ответ: а) \(1\frac{1}{18}\); б) \(1\frac{17}{60}\).