Question

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Answer 1

512)
х = 0,5
у = 1,5


513)
$1)( frac{5}{21} + frac{2}{15} ) + frac{2}{21} = frac{25}{105} + frac{14}{105} + frac{10}{105} = frac{49}{105} = frac{7}{15} \ \ 2)( frac{2}{35} + frac{3}{28} ) + frac{1}{28} = frac{8}{140} + frac{15}{140} + frac{5}{140} = frac{28}{140} = frac{1}{5} \ \ 3)( frac{7}{30} + frac{8}{45} ) + ( frac{2}{45} + frac{1}{30} ) = frac{21}{90} + frac{16}{90} + frac{4}{90} + frac{3}{90} = frac{44}{90} = frac{22}{45} \ \ 4)( frac{5}{24} + frac{11}{60} ) + ( frac{13}{60} + frac{1}{24} ) = frac{25}{120} + frac{22}{120} + frac{26}{120} + frac{5}{120} = frac{78}{120} = frac{13}{20}$