Question

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Answer 1

Ответ:

$1. \frac{3}{4} + \frac{7}{25} = \frac{75 + 28}{100} = \frac{103}{100} = 1 \frac{3}{100} \\ 2. \frac{1}{2} - \frac{49}{20} = \frac{10 - 49}{20} = \frac{ - 39}{20} = - \frac{39}{20} = - 1 \frac{19}{20} \\ 3. \frac{21}{5} \times \frac{3}{7} = \frac{3}{5} \times 3 = \frac{9}{5} = 1 \frac{4}{5} \\ 4. \frac{4}{5} \div \frac{2}{7} = \frac{4}{5} \times \frac{7}{2} = \frac{2}{5} \times 7 = \frac{14}{5} = 2 \frac{4}{5} \\ 5. \frac{1}{ \frac{1}{18} - \frac{1}{21} } = \frac{1}{ \frac{1}{126} } = 1 \div \frac{1}{126} = 1 \times 126 = 126 \\ 6.1 \frac{1}{12} \div (1 \frac{13}{18} - 2 \frac{5}{9} ) = \frac{13}{ 12} \div ( \frac{31}{18} - \frac{23}{9} ) = \frac{13}{12} \div ( - \frac{5}{6} ) = - \frac{13}{12} \times \frac{6}{5} = - \frac{13}{2} \times \frac{1}{5} = - \frac{13}{10} = - 1 \frac{3}{10} \\ 7.( \frac{4}{9} - 3 \frac{1}{15} ) \times 9 = ( \frac{4}{9} - \frac{46}{15} ) \times 9 = - \frac{118}{45} \times 9 = - \frac{118}{5} = - 23 \frac{3}{5} \\ 8. \frac{0.8}{1 - \frac{1}{9} } = \frac{ \frac{4}{5} }{ \frac{8}{9} } = \frac{4}{5} \div \frac{8}{9} = \frac{4}{5} \times \frac{9}{8} = \frac{1}{5} \times \frac{9}{2} = \frac{9}{10} \\ 9.( \frac{8}{19} - \frac{17}{38} ) \times \frac{19}{5} = - \frac{1}{38} \times \frac{19}{5} = - \frac{1}{2} \times \frac{1}{5} = - \frac{1}{10} \\ 10.9.8 + 8.6 = 9 \frac{8}{10} + 8 \frac{6}{10} = (9 + 8) + ( \frac{8}{10} + \frac{6}{10} ) = 17 + \frac{7}{5} = 17 + 1 \frac{2}{5} = 18 \frac{2}{5} \\ 11.6.4 - 4.8 = 6 \frac{4}{10} - 4 \frac{8}{10} = \frac{64}{10} - \frac{48}{10} = \frac{16}{10} = \frac{8}{5}$