1. Найдите значение выражения: a) 3.4 20.4 б) 2 1 5 12 2 5 в) 1,17 4 15

1. Найдем значение выражения. a) $$ \frac{3,4}{20,4} = \frac{34}{204} = \frac{17 \cdot 2}{17 \cdot 12} = \frac{2}{12} = \frac{1}{6}. $$ b) $$ \frac{2 \frac{1}{5}}{\frac{12}{5}} = \frac{\frac{2 \cdot 5 + 1}{5}}{\frac{12}{5}} = \frac{\frac{11}{5}}{\frac{12}{5}} = \frac{11}{5} : \frac{12}{5} = \frac{11}{5} \cdot \frac{5}{12} = \frac{11}{12}. $$ c) $$ \frac{1,17}{\frac{4}{15}} = 1,17 : \frac{4}{15} = \frac{117}{100} : \frac{4}{15} = \frac{117}{100} \cdot \frac{15}{4} = \frac{117}{20 \cdot 5} \cdot \frac{3 \cdot 5}{4} = \frac{117 \cdot 3}{20 \cdot 4} = \frac{351}{80} = 4 \frac{31}{80}. $$ Ответ: а) $$\frac{1}{6}$$, b) $$ \frac{11}{12}$$, c) $$4 \frac{31}{80}$$