нахождение значения выражения: а) $$3 \frac{3}{11} \cdot 7 \frac{1}{3}$$ б) $$10 \frac{2}{7} : 1 \frac{2}{9}$$ в) $$2\frac{1}{2} - \frac{18}{25}$$ г) $$5\frac{1}{7} - 3\frac{3}{9}$$

Решение:

1. $$3\frac{3}{11} \cdot 7\frac{1}{3} = \frac{36}{11} \cdot \frac{22}{3} = \frac{36 \cdot 22}{11 \cdot 3} = \frac{12 \cdot 2 \cdot 11 \cdot 2}{11 \cdot 3} = 12 \cdot 2 \cdot 2 = 48$$
2. $$10\frac{2}{7} : 1\frac{2}{9} = \frac{72}{7} : \frac{11}{9} = \frac{72}{7} \cdot \frac{9}{11} = \frac{648}{77} = 8\frac{32}{77}$$
3. $$2\frac{1}{2} - \frac{18}{25} = \frac{5}{2} - \frac{18}{25} = \frac{125 - 36}{50} = \frac{89}{50} = 1\frac{39}{50}$$
4. $$5\frac{1}{7} - 3\frac{3}{9} = 5\frac{1}{7} - 3\frac{1}{3} = \frac{36}{7} - \frac{10}{3} = \frac{108 - 70}{21} = \frac{38}{21} = 1\frac{17}{21}$$

Ответ: $$48$$, $$8\frac{32}{77}$$, $$1\frac{39}{50}$$, $$1\frac{17}{21}$$.