3. Вычислите: а) \(\frac{2}{13}\) + \(\frac{5}{13}\); б) \(\frac{4}{5}\) - \(\frac{3}{4}\); в) \(\frac{2}{15}\) + \(\frac{1}{3}\); г) \(\frac{5}{16}\) - \(\frac{1}{24}\).

Для сложения и вычитания дробей необходимо привести их к общему знаменателю.

1. а) \(\frac{2}{13}\) + \(\frac{5}{13}\) = \(\frac{2+5}{13}\) = \(\frac{7}{13}\)
2. б) \(\frac{4}{5}\) - \(\frac{3}{4}\) = \(\frac{4 \cdot 4}{5 \cdot 4}\) - \(\frac{3 \cdot 5}{4 \cdot 5}\) = \(\frac{16}{20}\) - \(\frac{15}{20}\) = \(\frac{16-15}{20}\) = \(\frac{1}{20}\)
3. в) \(\frac{2}{15}\) + \(\frac{1}{3}\) = \(\frac{2}{15}\) + \(\frac{1 \cdot 5}{3 \cdot 5}\) = \(\frac{2}{15}\) + \(\frac{5}{15}\) = \(\frac{2+5}{15}\) = \(\frac{7}{15}\)
4. г) \(\frac{5}{16}\) - \(\frac{1}{24}\) = \(\frac{5 \cdot 3}{16 \cdot 3}\) - \(\frac{1 \cdot 2}{24 \cdot 2}\) = \(\frac{15}{48}\) - \(\frac{2}{48}\) = \(\frac{15-2}{48}\) = \(\frac{13}{48}\)

Ответ: а) \(\frac{7}{13}\); б) \(\frac{1}{20}\); в) \(\frac{7}{15}\); г) \(\frac{13}{48}\)