Решение задания 3

1. $$\frac{1}{\frac{1}{30} + \frac{1}{42}} = \frac{1}{\frac{42 + 30}{30 \times 42}} = \frac{1}{\frac{72}{1260}} = \frac{1260}{72} = \frac{630}{36} = \frac{315}{18} = \frac{105}{6} = \frac{35}{2} = 17.5$$

   Ответ: 17.5

2. $$\frac{1}{\frac{1}{36} - \frac{1}{44}} = \frac{1}{\frac{44 - 36}{36 \times 44}} = \frac{1}{\frac{8}{1584}} = \frac{1584}{8} = 198$$

   Ответ: 198

3. $$\frac{1}{\frac{1}{36} + \frac{1}{45}} = \frac{1}{\frac{45 + 36}{36 \times 45}} = \frac{1}{\frac{81}{1620}} = \frac{1620}{81} = \frac{180}{9} = 20$$

   Ответ: 20

4. $$\frac{1}{\frac{1}{35} - \frac{1}{60}} = \frac{1}{\frac{60 - 35}{35 \times 60}} = \frac{1}{\frac{25}{2100}} = \frac{2100}{25} = \frac{420}{5} = 84$$

   Ответ: 84

5. $$\frac{1}{\frac{1}{21} + \frac{1}{28}} = \frac{1}{\frac{28 + 21}{21 \times 28}} = \frac{1}{\frac{49}{588}} = \frac{588}{49} = 12$$

   Ответ: 12

6. $$\frac{1}{\frac{1}{72} - \frac{1}{99}} = \frac{1}{\frac{99 - 72}{72 \times 99}} = \frac{1}{\frac{27}{7128}} = \frac{7128}{27} = \frac{2376}{9} = 264$$

   Ответ: 264