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a)\(\dfrac{a}{b}=5-\dfrac{3}{5}=\dfrac{25}{5}-\dfrac{3}{5}=\dfrac{22}{5}\)
b)\(\dfrac{a}{b}=\dfrac{5}{6}+\dfrac{4}{7}=\dfrac{35}{42}+\dfrac{24}{42}=\dfrac{59}{42}\)
c)\(\dfrac{a}{b}=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{3}{5}\times\dfrac{3}{2}=\dfrac{9}{10}\)
\(=>\dfrac{a}{b}\times\left(-\dfrac{2}{7}+\dfrac{5}{7}\right)=\dfrac{5}{7}\)
\(=>\dfrac{a}{b}\times\dfrac{3}{7}=\dfrac{5}{7}=>\dfrac{a}{b}=\dfrac{5}{7}:\dfrac{3}{7}=\dfrac{5}{3}\)
vậy \(\dfrac{a}{b}=\dfrac{5}{3}\)
\(\Rightarrow\dfrac{a}{b}\times\left(-\dfrac{2}{7}+\dfrac{5}{7}\right)=\dfrac{5}{7}\\ \Rightarrow\dfrac{a}{b}\times\dfrac{3}{7}=\dfrac{5}{7}\\ \Rightarrow\dfrac{a}{b}=\dfrac{5}{7}:\dfrac{3}{7}\\ \Rightarrow\dfrac{a}{b}=\dfrac{5}{3}\\ \Rightarrow a=5;b=3\)
bài 1
a)\(=\dfrac{16}{40}+\dfrac{15}{40}=\dfrac{31}{40}\)
b)\(=\dfrac{7}{6}-\dfrac{4}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)
c)\(=\dfrac{30}{9}=\dfrac{10}{3}\)
d)\(=\dfrac{8}{5}\times\dfrac{7}{4}=\dfrac{56}{20}=\dfrac{14}{5}\)
a) \(\dfrac{2}{5}\times?=\dfrac{3}{10}\)
\(?=\dfrac{3}{10}:\dfrac{2}{5}=\dfrac{3}{4}\)
b) \(\dfrac{1}{8}:?=\dfrac{1}{5}\)
\(?=\dfrac{1}{8}:\dfrac{1}{5}=\dfrac{5}{8}\)
a: Phân số cần tìm là: \(\dfrac{3}{10}:\dfrac{2}{5}=\dfrac{3}{10}\cdot\dfrac{5}{2}=\dfrac{15}{20}=\dfrac{3}{4}\)
b: Phân số cần tìm là \(\dfrac{1}{8}:\dfrac{1}{5}=\dfrac{5}{8}\)
`a, x-2=7/15`
`=>x=7/15 +2`
`=>x= 7/15+ 30/15`
`=>x= 37/15`
`b, 9/20 +x=2/5 +3/20`
`=> 9/20 +x=8/20 +3/20`
`=> 9/20 +x=11/20`
`=>x=11/20-9/20`
`=>x= 2/20=1/10`
x = \(\dfrac{7}{15}\) + 2 = \(\dfrac{37}{15}\)
x = \(\dfrac{2}{5}\) + \(\dfrac{3}{20}\) - \(\dfrac{9}{20}\) = \(\dfrac{1}{10}\)
a) \(\dfrac{3}{5}+\dfrac{1}{6}=\dfrac{18}{30}+\dfrac{5}{30}=\dfrac{23}{30}\)
b) \(4+\dfrac{2}{5}=\dfrac{20}{5}+\dfrac{2}{5}=\dfrac{22}{5}\)
c) \(\dfrac{25}{12}-\dfrac{7}{6}=\dfrac{25}{12}-\dfrac{14}{12}=\dfrac{11}{12}\)
d) \(\dfrac{9}{7}-\dfrac{7}{6}=\dfrac{54}{42}-\dfrac{49}{42}=\dfrac{5}{42}\)
d) \(\dfrac{3}{7}\times\dfrac{2}{5}=\dfrac{3\times2}{7\times5}=\dfrac{6}{35}\)
a) \(\dfrac{2}{7}\times\dfrac{4}{3}+\dfrac{2}{6}\)
\(=\dfrac{8}{21}+\dfrac{2}{6}\)
\(=\dfrac{5}{7}\)
b) \(\dfrac{4}{7}:2+\dfrac{4}{7}\)
\(=\dfrac{2}{7}+\dfrac{4}{7}\)
\(=\dfrac{6}{7}\)
c) \(\dfrac{1}{3}+\dfrac{3}{4}-\dfrac{1}{5}:\dfrac{2}{3}\)
\(=\dfrac{13}{12}-\dfrac{3}{10}\)
\(=\dfrac{47}{60}\)
a \(\dfrac{8}{21}+\dfrac{2}{6}=\dfrac{16}{42}+\dfrac{14}{42}=\dfrac{30}{42}=\dfrac{5}{7}\)
\(b\) \(\dfrac{4}{7}\times\dfrac{1}{2}+\dfrac{4}{7}=\dfrac{2}{7}+\dfrac{4}{7}=\dfrac{6}{7}\)
\(c\) \(\dfrac{1}{3}+\dfrac{3}{4}-\dfrac{1}{5}\times\dfrac{3}{2}=\dfrac{1}{3}+\dfrac{3}{4}-\dfrac{3}{10}=\dfrac{20}{60}+\dfrac{45}{60}-\dfrac{18}{60}=\dfrac{47}{60}\)
a) x=24/35 -2/7
x=14/35
b) x=7/8+5/6
x=41/24
c) x-11/5=3/5
x=11/5+3/5
x=14/5
tick cho mình nhé
a/b: 1/2 + 2/7 = 5/7
a/b:1/2=3/7
a/b=3/14
\(\dfrac{a}{b}:\dfrac{1}{2}+\dfrac{2}{7}=\dfrac{5}{7}\)
\(\Leftrightarrow\dfrac{a}{b}:\dfrac{1}{2}=\dfrac{3}{7}\)
\(\Leftrightarrow\dfrac{a}{b}=\dfrac{3}{7}\cdot\dfrac{1}{2}=\dfrac{3}{14}\)