Question

Решите задание 85,86 пожалуйста

Answer 1

Ответ:

Пошаговое объяснение:

$1)\frac{1}{3} x+\frac{1}{5}x+\frac{1}{6} x=\frac{21}{40} \\ \\ \frac{10}{30} x+\frac{6}{30}x+\frac{5}{30} x=\frac{21}{40}\\ \\ \frac{21}{30} x=\frac{21}{40} \\ \\ x=\frac{21}{40}*\frac{30}{21} \\ \\ x=\frac{3}{4}$

$2) 5\frac{1}{4}x-2\frac{2}{3}=1\frac{5}{12} \\ \\ 5\frac{1}{4}x=1\frac{5}{12}+2\frac{2}{3}\\ \\ 5\frac{1}{4}x=1\frac{5}{12}+2\frac{8}{12}\\ \\ 5\frac{1}{4}x=3\frac{13}{12}\\ \\ x=3\frac{13}{12} :5\frac{1}{4} \\ \\ x=\frac{49}{12} :\frac{21}{4} \\ \\ x=\frac{49}{12} *\frac{4}{21} \\ \\ x=\frac{7}{9}$

$3)8\frac{4}{15} -5\frac{2}{5}x=4\frac{2}{3} \\ \\ 5\frac{2}{5} x=8\frac{4}{15} -4\frac{2}{3} \\ \\ 5\frac{2}{5} x=8\frac{4}{15} -4\frac{10}{15}\\ \\ 5\frac{2}{5}x=3\frac{9}{15}\\ \\ x=3\frac{3}{5}: 5\frac{2}{5}\\ \\ x=\frac{18}{5} :\frac{27}{5} \\ \\ x=\frac{18}{5}*\frac{5}{27}\\ \\ x=\frac{2}{3}$

$4)\frac{11}{24} x+7\frac{1}{3} =9\frac{5}{8} \\ \\ \frac{11}{24}x=9\frac{5}{8} -7\frac{1}{3} \\ \\ \frac{11}{24}x=9\frac{15}{24} -7\frac{8}{24} \\ \\ \frac{11}{24} x=2\frac{7}{24} \\ \\ x=2\frac{7}{24} :\frac{11}{24} \\ \\ x=\frac{55}{24} *\frac{24}{11} \\ \\ x=5$

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№86

$(6\frac{4}{5} -2\frac{3}{4} ):(2\frac{16}{21} +3\frac{2}{3} )=(6\frac{16}{20} -2\frac{15}{20} ):(2\frac{16}{21} +3\frac{14}{21} )=4\frac{1}{20} :5\frac{30}{21} = 4\frac{1}{20} :5\frac{10}{7} =\frac{81}{20} :\frac{45}{7} =\frac{81}{20} *\frac{7}{45} =\frac{63}{100}$