\(a,\frac{5}{6}+x\)x \(\frac{3}{4}=3\)

\(x\)x \(\frac{3}{4}=3-\frac{5}{6}\)

\(x\)x \(\frac{3}{4}=\frac{13}{6}\)

\(x=\frac{13}{6}:\frac{3}{4}\)

\(x=\frac{26}{9}\)

b, \(5\frac{1}{6}-x:\frac{3}{4}=\frac{2}{3}\)

\(\frac{31}{6}-x:\frac{3}{4}=\frac{2}{3}\)

\(x:\frac{3}{4}=\frac{31}{6}-\frac{2}{3}\)

\(x:\frac{3}{4}=\frac{9}{2}\)

\(x=\frac{9}{2}\)x \(\frac{3}{4}\)

\(x=\frac{27}{8}\)

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Thank you!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

\(\frac{3}{4}+\frac{2}{3}=\frac{9}{12}+\frac{8}{12}=\frac{17}{12}\)

\(\frac{9}{2}-4=\frac{9}{2}-\frac{8}{2}=\frac{1}{2}\)

\(\frac{4}{5}\times\frac{3}{2}=\frac{4\times3}{5\times2}=\frac{12}{10}=\frac{6}{5}\)

\(\frac{5}{6}:\frac{6}{5}=\frac{5}{6}\times\frac{5}{6}=\frac{25}{36}\)

giúp với ạ

giải dc nhưng mà hoi lâu

\(a,\frac{2}{3}+\frac{4}{5}=\frac{10}{15}+\frac{12}{15}=\frac{22}{15}\)

\(b,\frac{5}{12}+\frac{1}{6}=\frac{5}{12}+\frac{2}{12}=\frac{7}{12}\)

\(c,\frac{3}{4}+\frac{5}{6}=\frac{9}{12}+\frac{10}{12}=\frac{19}{12}\)

a)22/15

b)7/12

c)19/12

bài 1:

\(\frac{6}{11}+\frac{1}{3}+\frac{5}{11}\)

\(=\left(\frac{6}{11}+\frac{5}{11}\right)+\frac{1}{3}\)

\(=\frac{11}{11}+\frac{1}{3}=1+\frac{1}{3}=\frac{3}{3}+\frac{1}{3}=\frac{4}{3}\)

bài 2:

\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}\)

\(=\left(\frac{1}{2}+\frac{1}{20}\right)+\left(\frac{1}{6}+\frac{1}{12}\right)\)

\(=\frac{11}{20}+\frac{1}{4}=\frac{11}{20}+\frac{5}{20}=\frac{15}{20}=\frac{3}{4}\)

bài 3: 

a) \(\frac{3}{2}\cdot\frac{4}{5}\cdot\frac{2}{3}=\left(\frac{3}{2}\cdot\frac{2}{3}\right)\cdot\frac{4}{5}=1\cdot\frac{4}{5}=\frac{4}{5}\)

b) \(\frac{6}{7}\cdot\frac{5}{3}\cdot\frac{7}{6}=\left(\frac{6}{7}\cdot\frac{7}{6}\right)\cdot\frac{5}{3}=1\cdot\frac{5}{3}=\frac{5}{3}\)

bài 4: 

a) \(\frac{2}{5}\cdot\frac{1}{4}+\frac{3}{4}\cdot\frac{2}{5}=\frac{2}{5}\cdot\left(\frac{1}{4}+\frac{3}{4}\right)=\frac{2}{5}\cdot1=\frac{2}{5}\)

b) \(\frac{6}{11}:\frac{2}{3}+\frac{5}{11}:\frac{2}{3}=\left(\frac{6}{11}+\frac{5}{11}\right):\frac{2}{3}=1:\frac{2}{3}=\frac{3}{2}\)

Bài 1: 

  6/11 + 1/3 + 5/11 

= ( 6/11 + 5/11) + 1/3

= 11/11 + 1/3

= 1 + 1/3 

= 3/3 +1/3  

= 4/3 

Bài 2: 

1/2 + 1/6 + 1/12 + 1/20 

= ( 1/2 + 1/6 + 1/12 ) + 1/20 

= ( 6/12 + 2/12 + 1/12 ) + 1/20 

=9/12 + 1/20 

= 3/4 +1/20  

= 15/20 + 1/20 

= 16/20 = 4/5

 Bài 3:

a) \(\frac{3}{2}\times\frac{4}{5}\times\frac{2}{3}\) \(=\left(\frac{3}{2}\times\frac{2}{3}\right)\times\frac{4}{5}\)\(=1\times\frac{4}{5}=\frac{4}{5}\) 

b)  \(\frac{6}{7}\times\left(\frac{5}{3}\times\frac{7}{6}\right)\) \(=\frac{6}{7}\times\frac{35}{18}\)\(=\frac{1\times5}{7\times3}=\frac{5}{21}\)   

Bài 4:

a) 2/5  x 1/4 + 3/4 x 2/5 

= 2/5 x ( 1/4  + 3/4) 

 = 2/5 x  1 

= 2/5

 b) 6/11 : 2/3 +5/11 : 2/3 

=  ( 6/11 + 5/11) x 3/2 

= 11/11 x 3/2  

= 1 x 3/2  

=  3/2  

....  

a) Mẫu số chung: 6

\(\frac{1}{2}=\frac{1.3}{2.3}=\frac{3}{6}\) (Dấu . là dấu x nha)

\(\frac{2}{3}=\frac{2.2}{3.2}=\frac{4}{6}\)

Và \(\frac{1}{6}\)

b) Mẫu số chung: 28

\(\frac{4}{7}=\frac{4.4}{7.4}=\frac{16}{28}\)

\(\frac{3}{4}=\frac{3.7}{4.7}=\frac{21}{28}\)

c) Mẫu số chung: 24

\(\frac{5}{4}=\frac{5.6}{4.6}=\frac{30}{24}\)

\(\frac{5}{6}=\frac{5.4}{6.4}=\frac{20}{24}\)

\(x+\frac{3}{4}=\frac{5}{3}\)                                           \(\frac{7}{5}:x=3\)                                        \(2-x=\frac{4}{7}\)

x =\(\frac{5}{3}-\frac{3}{4}\)                                                x=\(\frac{7}{5}:3\)                                                     x=\(2-\frac{4}{7}\)

x=\(\frac{11}{12}\)                                                           x=\(\frac{7}{15}\)                                                        x=\(\frac{10}{7}\)

\(a.\frac{3}{7}.\frac{5}{6}+\frac{5}{6}.\frac{4}{7}=\left(\frac{3}{7}+\frac{4}{7}\right).\frac{5}{6}=1.\frac{5}{6}=\frac{5}{6}\)

\(b.\frac{1}{6}:\frac{4}{5}+\frac{1}{8}:\frac{4}{5}=\left(\frac{1}{6}+\frac{1}{8}\right):\frac{4}{5}=\left(\frac{4}{24}+\frac{3}{24}\right):\frac{4}{5}=\frac{7}{24}:\frac{4}{5}=\frac{7.5}{24.4}\)\(=\frac{35}{96}\)

\(c.\frac{1}{6}:\frac{4}{5}-\frac{1}{8}:\frac{4}{5}=\left(\frac{1}{6}-\frac{1}{8}\right):\frac{4}{5}=\left(\frac{4}{24}-\frac{3}{24}\right):\frac{4}{5}\)\(=\frac{1}{24}:\frac{4}{5}=\frac{1.5}{24.4}=\frac{5}{96}\)

a) \(\frac{3}{7}\cdot\frac{5}{6}+\frac{5}{6}\cdot\frac{4}{7}\)

\(=\left(\frac{3}{7}+\frac{4}{7}\right)\cdot\frac{5}{6}\)

\(=1\cdot\frac{5}{6}\)

\(=\frac{5}{6}\)

b) \(\frac{1}{6}:\frac{4}{5}+\frac{1}{8}:\frac{4}{5}\)

\(=\left(\frac{1}{6}+\frac{1}{8}\right):\frac{4}{5}\)

\(=\frac{7}{24}:\frac{4}{5}\)

\(=\frac{35}{96}\)

c) \(\frac{1}{6}:\frac{4}{5}-\frac{1}{8}:\frac{4}{5}\)

\(=\left(\frac{1}{6}-\frac{1}{8}\right):\frac{4}{5}\)

\(=\frac{1}{24}:\frac{4}{5}\)

\(=\frac{5}{96}\)

\(3+\frac{2}{5}-\frac{3}{4}\times\frac{4}{5}\)

\(=3+\frac{2}{5}-\frac{3}{4}\)

\(=\frac{3\times20+2\times4-3\times5}{20}\)

\(=\frac{60+8-15}{20}\)

\(=\frac{68-15}{20}\)

\(=\frac{53}{20}\)

\(5-\frac{7}{9}+\frac{2}{3}-\frac{5}{6}:\frac{4}{9}\)

\(=5-\frac{7}{9}+\frac{2}{3}-\frac{45}{24}\)

\(=\frac{5\times72-7\times8+2\times24-45\times3}{72}\)

\(=\frac{360-56+48-135}{72}\)

\(=\frac{217}{72}\)