10. Вычислите: 1) $\frac{15}{20}+\frac{42}{30}-\frac{56}{40}$; 2) $\left(\frac{1}{2}-\frac{1}{3}\right)+\left(\frac{1}{3}-\frac{1}{4}\right)$; 3) $\frac{17}{51}+\frac{19}{57}-\frac{13}{39}$; 4) $\frac{2}{3}+1\frac{1}{2}-\frac{1}{4}$; 5) $\left(\frac{3}{6}-\frac{1}{4}\right)+\left(\frac{1}{2}-\frac{1}{3}\right)$; 6) $\left(1\frac{3}{5}-\frac{3}{10}\right)+\left(\frac{1}{4}-\frac{1}{8}\right)$.

Question

Вопрос: $Фото задания: 10. Вычислите: 1) $\frac{15}{20}+\frac{42}{30}-\frac{56}{40}$; 2)…$ Фото задания

Accepted Answer

$\frac{15}{20}+\frac{42}{30}-\frac{56}{40}=\frac34+\frac75-\frac75=\frac34$.
$\left(\frac12-\frac13\right)+\left(\frac13-\frac14\right)=\frac16+\frac1{12}=\frac14$.
$\frac{17}{51}+\frac{19}{57}-\frac{13}{39}=\frac13+\frac13-\frac13=\frac13$.
$\frac23+1\frac12-\frac14=\frac23+\frac32-\frac14=\frac8{12}+\frac{18}{12}-\frac3{12}=\frac{23}{12}=1\frac{11}{12}$.
$\left(\frac36-\frac14\right)+\left(\frac12-\frac13\right)=\left(\frac12-\frac14\right)+\frac16=\frac14+\frac16=\frac5{12}$.
$\left(1\frac35-\frac3{10}\right)+\left(\frac14-\frac18\right)=\left(\frac85-\frac3{10}\right)+\frac18=\frac{13}{10}+\frac18=\frac{52}{40}+\frac5{40}=\frac{57}{40}=1\frac{17}{40}$.

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