а) \[2\frac{1}{7}+3\frac{5}{7}=5\frac{6}{7}\]
б) \[7\frac{1}{5}-5\frac{3}{5}=6\frac{6}{5}-5\frac{3}{5}=1\frac{3}{5}\]
Ответ: а) 5\(\frac{6}{7}\); б) 1\(\frac{3}{5}\).