Bài 1: 

Ta có: \(x-35\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow65\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow x=\dfrac{1}{25}:\dfrac{13}{20}=\dfrac{1}{25}\cdot\dfrac{20}{13}=\dfrac{4}{65}\)

Vậy: \(x=\dfrac{4}{65}\)

Bài 2: 

a) Ta có: \(17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)\)

\(=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=11+\dfrac{2}{31}-\dfrac{15}{17}\)

\(=\dfrac{5366}{527}\)

= 23 . 41 + 59 . 23

= 23 . ( 41 + 59 )

= 23 . 100

= 2300

HỌC TỐT !

Tổng của dãy là:

23.41 + 59 .23

=23. (41+59)

=23.100

= 2300

1.73.(8-59)-59.(8-73)

=73.8-73.59-59.8-59.73

=73.(59-59)-8.(73-59)

=73.0-8.14

=0-112

=-112

2.159.(18-59)-59.(18 - 159)

=159.18-59.159-59.18-59.159

=159.(59-59)-18.(159-59)

=159.0-18.100

=0-1800

=-1800

Sửa đề: \(2x+\dfrac{11}{6}+\dfrac{23}{12}+\dfrac{39}{20}+\dfrac{59}{30}+\dfrac{83}{42}+\dfrac{111}{56}=12\)

\(\Leftrightarrow2x+\left(2+2+2+2+2+2\right)-\left(\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}\right)=12\)

\(\Leftrightarrow2x-\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{7}-\dfrac{1}{8}\right)=0\)

\(\Leftrightarrow2x-\dfrac{3}{8}=0\)

hay x=3/16

1. \(=\left(-23+27-13+47-23+37-13+47\right):45\)\(=\left(-23.2-13.2+27.2+47.2\right):45=\left(-72+148\right):45=\frac{76}{45}\)
2. \(=59:\left(111-522+115-23\right)=59:\left(-319\right)\)

oc cho

( -2007 ) - ( 12 - 2007 )

= -2007 - 12 + 2007

= ( -2007 + 2007 ) -12

= 0 -12

= -12

( 28 + 39 ) + ( 168 - 28 - 39 )

= 28 + 39 + 168 - 28 - 39

= ( 28 - 28 ) + ( 39 - 39 ) + 168

= 0 + 0 + 168

= 168

( 23 - 145 + 59 ) - ( 23 + 59 )

= 23 - 145 + 59 - 23 - 59

= ( 23 - 23 ) + ( 59 - 59 ) -145

= 0 + 0 - 145

= -145

( -23 ) - ( 77 + 1000 )

= -23 - 77 + 1000

= ( -23 -77 ) + 1000

= -1000 + 1000

= 0

( 427 - 2019 ) - ( 27 - 2019 )

= 427 - 2019 - 27 + 2019

= ( 427 - 27 ) - ( 2019 - 2019 )

= 400 - 0

= 400

Bạn k cho mk nha !!!

3 x ( X -18) +23 = 59

3 x ( X -18 )       = 59 - 23

3 x ( X - 18)       =    36

        X - 18         = 36 : 3

         X - 18        =    12

          X         = 12 + 18

          X           = 30

k nha

3x(x-180+23=59

3x-18=59-23

3x-18=36

3x=36+18

3x=54

x=54:3

x=18

Vậy x=18