1) 7,8 * 4/13 - 61,5 : 13 2/3 + 198,8

Давай разберем эти примеры по порядку. 1) $7,8 \cdot \frac{4}{13} - 61,5 : 13\frac{2}{3} + 198,8$ - $7,8 = \frac{78}{10} = \frac{39}{5}$. Тогда: $\frac{39}{5} \cdot \frac{4}{13} = \frac{3 \cdot 13 \cdot 4}{5 \cdot 13} = \frac{12}{5} = 2,4$. - $61,5 = \frac{123}{2}$, $13\frac{2}{3} = \frac{41}{3}$. Тогда: $\frac{123}{2} : \frac{41}{3} = \frac{123}{2} \cdot \frac{3}{41} = \frac{3 \cdot 41 \cdot 3}{2 \cdot 41} = \frac{9}{2} = 4,5$. - $2,4 - 4,5 + 198,8 = 196,7$. 2) $19,25 \cdot \frac{5}{11} + 5,76 \cdot \frac{5}{12} - 13,08$ - $19,25 = \frac{77}{4}$. Тогда: $\frac{77}{4} \cdot \frac{5}{11} = \frac{7 \cdot 11 \cdot 5}{4 \cdot 11} = \frac{35}{4} = 8,75$. - $5,76 = \frac{576}{100} = \frac{144}{25}$. Тогда: $\frac{144}{25} \cdot \frac{5}{12} = \frac{12 \cdot 12 \cdot 5}{5 \cdot 5 \cdot 12} = \frac{12}{5} = 2,4$. - $8,75 + 2,4 - 13,08 = 11,15 - 13,08 = -1,93$. 3) $4,625 \cdot 2\frac{2}{15} : 2,96 - 2\frac{4}{7}$ - $4,625 = 4\frac{5}{8} = \frac{37}{8}$, $2\frac{2}{15} = \frac{32}{15}$. Тогда: $\frac{37}{8} \cdot \frac{32}{15} = \frac{37 \cdot 4}{15} = \frac{148}{15}$. - $2,96 = \frac{296}{100} = \frac{74}{25}$. Тогда: $\frac{148}{15} : \frac{74}{25} = \frac{148}{15} \cdot \frac{25}{74} = \frac{2 \cdot 74 \cdot 5 \cdot 5}{3 \cdot 5 \cdot 74} = \frac{10}{3} = 3\frac{1}{3}$. - $3\frac{1}{3} - 2\frac{4}{7} = \frac{10}{3} - \frac{18}{7} = \frac{70}{21} - \frac{54}{21} = \frac{16}{21}$. 4) $30,25 : 4\frac{5}{7} : 1,05 - 2\frac{1}{6}$ - $30,25 = \frac{121}{4}$, $4\frac{5}{7} = \frac{33}{7}$. Тогда: $\frac{121}{4} : \frac{33}{7} = \frac{121}{4} \cdot \frac{7}{33} = \frac{11 \cdot 11 \cdot 7}{4 \cdot 3 \cdot 11} = \frac{77}{12}$. - $1,05 = \frac{21}{20}$. Тогда: $\frac{77}{12} : \frac{21}{20} = \frac{77}{12} \cdot \frac{20}{21} = \frac{7 \cdot 11 \cdot 4 \cdot 5}{3 \cdot 4 \cdot 3 \cdot 7} = \frac{55}{9} = 6\frac{1}{9}$. - $6\frac{1}{9} - 2\frac{1}{6} = \frac{55}{9} - \frac{13}{6} = \frac{110}{18} - \frac{39}{18} = \frac{71}{18} = 3\frac{17}{18}$.