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`2/5 xx 4/7 + 3/5 xx 4/7`
`= 4/7 xx (2/5 + 3/5)`
`= 4/7 xx 1`
`= 4/7`
5/7+2/3-4/7+4/3
=(5/7+4/7)-(2/3+4/3)
=9/7+6/3
=27/21+42/21
=69/21
\(\dfrac{4}{7}x\left(\dfrac{2}{5}+\dfrac{3}{5}\right)=\dfrac{4}{7}x1=\dfrac{4}{7}\)
\(=\dfrac{3}{7}\left(\dfrac{5}{4}-\dfrac{2}{9}\right)=\dfrac{3}{7}\cdot\dfrac{45-8}{36}=\dfrac{3}{36}\cdot\dfrac{37}{7}=\dfrac{37}{84}\)
\(\dfrac{3}{7}:\dfrac{4}{5}-\dfrac{3}{7}:\dfrac{9}{2}\)
\(=\dfrac{3}{7}\times\dfrac{5}{4}-\dfrac{3}{7}\times\dfrac{2}{9}\)
\(=\dfrac{3}{7}\times\left(\dfrac{5}{4}-\dfrac{2}{9}\right)\)
\(=\dfrac{3}{7}\times\left(\dfrac{45}{36}-\dfrac{8}{36}\right)\)
\(=\dfrac{3}{7}\times\dfrac{37}{36}\)
\(=\dfrac{37}{84}\)
#DatNe
a: =8/15x1/4=2/15
b: \(=\dfrac{5}{3}\cdot\dfrac{4}{5}\cdot\dfrac{6}{7}=\dfrac{24}{21}=\dfrac{8}{7}\)
c: \(=\dfrac{2}{5}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\)
\(1.4\)
\(\frac{3}{7}+\frac{2}{5}+\frac{4}{7}\)
\(=\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{2}{5}\)
\(=\frac{7}{7}+\frac{2}{5}\)
\(=1+\frac{2}{5}\)
\(=\frac{1}{1}+\frac{2}{5}\)
\(=\frac{5}{5}+\frac{2}{5}\)
\(=\frac{7}{5}\)