13 a)÷ 1 = 17 19 б) 1÷= 23 1 3 в)÷= 5 4 5 1 г)÷= 8 2 3 9 д)÷= 7 14

a) $$\frac{13}{17} \div 1 = \frac{13}{17} \times \frac{1}{1} = \frac{13}{17}$$

Ответ: $$\frac{13}{17}$$

б) $$1 \frac{1}{23} = \frac{23+19}{23} = \frac{42}{23}$$

$$\frac{42}{23} = 1 \frac{19}{23}$$

Ответ: $$1\frac{19}{23}$$

в) $$\frac{1}{5} \div \frac{3}{4} = \frac{1}{5} \times \frac{4}{3} = \frac{4}{15}$$

Ответ: $$\frac{4}{15}$$

г) $$\frac{5}{8} \div \frac{1}{2} = \frac{5}{8} \times \frac{2}{1} = \frac{10}{8} = \frac{5}{4} = 1\frac{1}{4}$$

Ответ: $$1\frac{1}{4}$$

д) $$\frac{3}{7} \div \frac{9}{14} = \frac{3}{7} \times \frac{14}{9} = \frac{3 \times 14}{7 \times 9} = \frac{42}{63} = \frac{2}{3}$$

Ответ: $$\frac{2}{3}$$