Вычислите:а)3 1/5×3 1/8;б)1 4/11:1 2/13;в)2 3/4:1 3/8×3 2/7.

$a)3 \frac{1}{5} \times 3 \frac{1}{8} = \frac{16}{5} \times \frac{25}{8} = 2 \times 5 \\ = 10$
б)
$1 \frac{4}{11} \div 1 \frac{2}{13} = \frac{15}{11} \times \frac{13}{15} = \frac{13}{11 } = 1 \frac{2}{11}$
в)
$2 \frac{3}{4} \div 1 \frac{3}{8} \times 3 \frac{2}{7} = 6 \frac{4}{7}$
$2 \frac{3}{4} \div 1 \frac{3}{8} = \frac{11}{4} \times \frac{8}{11} = 2$
$2 \times 3 \frac{2}{7} = 2 \times \frac{23}{7} = \frac{46}{7} = 6 \frac{4}{7}$