\(\frac{5}{11}:\frac{2}{5}+\frac{3}{22}\)=\(\frac{25}{22}+\frac{3}{22}\)

                            =\(\frac{28}{22}\)= \(\frac{14}{11}\)

Gọi số cần tìm là abc, ta có 

abc9 = 26 x abc

abc0 + 9 = 26 x abc

abc x 10 + 9 = 26 x abc

9 = abc x ( 26 - 10)

9 = abc x 16

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

x=\(\frac{35}{10}\)-\(\frac{6}{10}\)=\(\frac{29}{10}\)

b) x=\(\frac{1}{5}\)+\(\frac{1}{4}\)

x=\(\frac{9}{20}\)

c) x= 2-\(\frac{4}{7}\)=\(\frac{10}{7}\)

d) x=4/7:2/5

x=4/5 x 5/2=10/7

a) \(x+\frac{3}{5}=\frac{7}{2}\)

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

\(x=\frac{35}{10}-\frac{6}{10}\)

\(x=\frac{29}{10}\)

vay \(x=\frac{29}{10}\)

b) \(x-\frac{1}{4}=\frac{1}{5}\)

\(x=\frac{1}{5}+\frac{1}{4}\)

\(x=\frac{4}{20}+\frac{5}{20}\)

\(x=\frac{9}{20}\)

vay \(x=\frac{9}{20}\)

c) \(2-x=\frac{4}{7}\)

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

\(x=\frac{14}{7}-\frac{4}{7}\)

\(x=\frac{10}{7}\)

vay \(x=\frac{10}{7}\)

d) \(\frac{2}{5}x=\frac{4}{7}\)

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

\(x=\frac{4}{7}.\frac{5}{2}\)

\(x=\frac{10}{7}\)

vay \(x=\frac{10}{7}\)

... / ../.../.../../...../

\(\frac{123}{12}=10\frac{1}{4}\)

\(\frac{25}{3}=8\frac{1}{3}\)

\(\frac{7}{4}=1\frac{3}{4}\)

\(\frac{123}{12}\)=10\(\frac{3}{12}\)

\(\frac{25}{3}\)=8\(\frac{1}{3}\)

25-2 : (3/5-1/2) + (5/2 +1/5 * 1/4 )

= 25 - 2 : 1/10 + (5/2 + 1/20)

= 25 - 20 + 51/20

= 5 + 51/20

= \(5\frac{51}{20}\)

( 3/10+ 4/5 *1/2 ) : (17/9 -4/3 : 3)

= (3/10 + 2/5) : (17/9 - 4/9)

= (-1/10) : 13/9

= -9/130

y + y * 1/3 + y : 2/7 = 58

=> y + y * 1/3 + y * 7/2 = 58

=> y * (1 + 1/3 + 7/2) = 58

=> y * 29/6 = 58

=> y = 58 : 29/6

=> y = 58 * 6/29

=> y = 12