3 3/7 + 2 1/5 + 5 4/7 : 5/6

$3 \frac{3}{7} + 2 \frac{1}{5} + 5 \frac{4}{7} \div \frac{5}{6} = 3 \frac{3}{7} + 2 \frac{1}{5} + 6 \frac{24}{35 } = 5 \frac{22}{35} + 6 \frac{24}{35} = 12 \frac{11}{35}$

(1)

$5 \frac{4}{7} \div \frac{5}{6} = \frac{5 \times 7 + 4}{7} \div \frac{5}{6} = \frac{39}{7} \times \frac{6}{5} = \frac{234}{35} = 6 \frac{24}{35}$

(2)

$3 \frac{3}{7} + 2 \frac{1}{5} = \frac{3 \times 7 + 3}{7} + \frac{2 \times 5 + 1}{5} = \frac{24}{7} + \frac{11}{5} = \frac{120 + 77}{35} = 5 \frac{22}{35}$

(3)

$5 \frac{22}{35} + 6 \frac{24}{35} = 11 \frac{22}{35} + \frac{24}{35} = 11 \frac{46}{35} = 12 \frac{11}{35}$