(-7 1/3+6 7/8):3/4+(-5 1/4 +4 21/10 ):1 9/20

$( - 7 \frac{1}{3} + 6 \frac{7}{8} ) \div \frac{3}{4} + ( - 5 \frac{1}{4} + 4 \frac{21}{10} ) \div 1 \frac{9}{20} .$

решаем по действиям :

$1) - 7 \frac{1}{3} + 6 \frac{7}{8} = 6 \frac{7}{8} - 7 \frac{1}{3} = \frac{55}{8} - \frac{22}{3} =$

$= \frac{165}{24} - \frac{176}{24} = - \frac{11}{24} .$

$2) - 5 \frac{1}{4} + 4 \frac{21}{10} = 4 \frac{21}{10} - 5 \frac{1}{4} = \frac{61}{10} - \frac{21}{4} =$

$= \frac{122}{20} - \frac{105}{20} = \frac{17}{20} .$

$3) - \frac{11}{24} \div \frac{3}{4} = - \frac{11}{24} \times \frac{4}{3} = - \frac{44}{72} = - \frac{11}{18} .$

$4) \frac{17}{20} \div 1 \frac{9}{20} = \frac{17}{20} \div \frac{29}{20} = \frac{17}{20} \times \frac{20}{29} = \frac{340}{580} =$

$= \frac{17}{29} .$

$5) - \frac{11}{18} + \frac{17}{29} = \frac{17}{29} - \frac{11}{18} = \frac{306}{522} - \frac{319}{522} =$

$= - \frac{13}{522}.$

Ответ :

$- \frac{13}{522} .$