4. Вычислить: а) \(\frac{13}{20}-\frac{7}{15}\); б) \(\frac{11}{16}+\frac{5}{12}\); в) \(\frac{19}{30}-\frac{2}{5}+\frac{1}{3}\).

а) \(\frac{13}{20}-\frac{7}{15}=\frac{39}{60}-\frac{28}{60}=\frac{11}{60}\).

б) \(\frac{11}{16}+\frac{5}{12}=\frac{33}{48}+\frac{20}{48}=\frac{53}{48}=1\frac{5}{48}\).

в) \(\frac{19}{30}-\frac{2}{5}+\frac{1}{3}=\frac{19}{30}-\frac{12}{30}+\frac{10}{30}=\frac{17}{30}\).

Ответ: а) \(\frac{11}{60}\); б) \(1\frac{5}{48}\); в) \(\frac{17}{30}\).