N° 142

{[(4/3-1/4)×(-2/13+3)-30/12]÷7/4-2/3}×3/5-2/5+1

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$\big\{\big[\big(\frac{4}{3}-\frac{1}{4}\big)×\big(-\frac{2}{13}+3\big)-\frac{30}{12}\big]÷\frac{7}{4}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=\big\{\big[\big(\frac{16-3}{12}\big)×\big(\frac{-2+39}{13}\big)-\frac{5}{2}\big]×\frac{4}{7}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=\big\{\big[\frac{13}{12}×\frac{37}{13}-\frac{5}{2}\big]×\frac{4}{7}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=\big\{\big[\frac{1}{12}×\frac{37}{1}-\frac{5}{2}\big]×\frac{4}{7}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=\big\{\big[\frac{37}{12}-\frac{5}{2}\big]×\frac{4}{7}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=\big\{\big[\frac{37-30}{12}\big]×\frac{4}{7}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=\big\{\frac{7}{12}×\frac{4}{7}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=\big\{\frac{1}{3}×\frac{1}{1}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=\big\{\frac{1}{3}-\frac{2}{3}\big\}×\frac{3}{5}-\frac{2}{5}+1=$

$=-\frac{1}{3}×\frac{3}{5}-\frac{2}{5}+1=$

$=-\frac{1}{1}×\frac{1}{5}-\frac{2}{5}+1=$

$=-\frac{1}{5}-\frac{2}{5}+1=$

$=-\frac{3}{5}+1=$

$=\frac{-3+5}{5}=$

$=\dfrac{2}{5}$