3. Вычислите: а) 3/11 + 5/11; б) 2/3 − 3/5; в) 7/16 + 1/2; г) 5/12 − 1/3.

1. \(\frac{3}{11}+\frac{5}{11}=\frac{8}{11}\).
2. \(\frac{2}{3}-\frac{3}{5}=\frac{10}{15}-\frac{9}{15}=\frac{1}{15}\).
3. \(\frac{7}{16}+\frac{1}{2}=\frac{7}{16}+\frac{8}{16}=\frac{15}{16}\).
4. \(\frac{5}{12}-\frac{1}{3}=\frac{5}{12}-\frac{4}{12}=\frac{1}{12}\).

Ответ: а) \(\frac{8}{11}\); б) \(\frac{1}{15}\); в) \(\frac{15}{16}\); г) \(\frac{1}{12}\).