Question

Решите пожалуйста понятно и с разбором

Answer 1

Ответ:

6. $-2 \frac{2}{3}+2\frac{1}{3}+(-15\frac{3}{7}:\frac{4}{15})=\frac{-8}{3}+\frac{7}{3}+(\frac{-108}{7}:\frac{4}{15})=\frac{-8}{3}+\frac{7}{3}+\frac{-108*15}{7*4}=\frac{-8}{3}+\frac{7}{3}+\frac{-405}{7}=\frac{-8*7+7*7-405*3}{21}=\frac{-1222}{21}=-58\frac{4}{21}$

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7. $\frac{8}{15}*(2\frac{1}{4}-7\frac{1}{2})-\frac{7}{30}*(4\frac{2}{7}-8\frac{4}{7})=\frac{8}{15}*(\frac{9}{4}-\frac{15}{2})-\frac{7}{30}*(\frac{30}{7}-\frac{60}{7})=\frac{8}{15}=\frac{8}{15}*\frac{9-15*2}{4}-\frac{7}{30}*\frac{30*60}{7}=\frac{8}{15}*\frac{-21}{4}-\frac{7}{30}*\frac{-30}{7}=\frac{-8*21}{15*4}-\frac{-7*30}{30*7}=\frac{-14}{5}-\frac{-1}{1}=\frac{-14+1*5}{5}=\frac{-9}{5}=-1\frac{4}{5}$

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8. $7,8-0,4x=20:5\\7,8-0,4x=4\\-0,4x=4-7,8\\-0,4x=-3,8\\x=9,5$

Пошаговое объяснение: