13.(23+22)-3(17+28)

=13.45-3.45

=(13-3).45

=10.45

=450

​Tick mình mình là người đầu tiên nhákudosinichi

13.(23+22)-3(17+28)

=13.45-3.45

=45.(13-3)

=45.10

=450

tick nha

\(a,-215-358+215+\left(-42\right)\\ =\left(-215+215\right)+\left(-358-42\right)\\ =0-400\\ =-400\\ b,13\cdot\left(23+22\right)-3\cdot\left(17+28\right)\\ =13\cdot45-3\cdot45\\ =45\cdot\left(13-3\right)\\ =45\cdot10\\ =450\)

( -12 ).47 + ( - 12 ).52 + ( -12 ) 

= ( -12 ).( 47 + 52 + 1 ) 

= ( -12 ).100

= -1200

13.(23 + 22 ) - 3.( 17 + 28 ) 

= 13.45 - 3.45

= 45.(13 - 3 ) 

= 45.10

=450

(-12).47 + (-12).52 + (-12)

= (-12).47 + (-12).52 + (-12).1

= (-12) . ( 47+52+1)

= (-12) .100

= -1200.

(-12).47+(-12).52+(-12)

=(-12).(47+52+1)

=-1200

13.(23+22)-3.(17+28)

=13.45-3.45

=45.(13-3)

=450

happy new year

\(13.\left(23+22\right)-3.\left(17+28\right)\)

\(=13.23+22-3.17+28\)

\(=13.\left(23+17\right)-3\left(22+28\right)\)

\(=13.40-3.50\)

\(=520-150=370\)

\(-48+48.\left(-78\right)+48.\left(-21\right)\)

\(=48.\left[-78+\left(-21\right)-1\right]\)

\(=48.\left(-100\right)=-4800\)

Bài này giống bài 1 trong bài thi cuối kì của trường tôi thế nhỉ

`a)3/5+(-4/9)`

`=3/5-4/9`

`=27/45-20/45`

`=7/45`

`b)3/5+2/5 . 15/8`

`=3/5 + 30/40`

`=3/5+3/4`

`=12/20+15/20`

`=27/20`

`c)7/2 . 8/13 + 8/13 . (-5/2)`

`=8/13 . (7/2 +(-5)/2)`

`=8/13 . 1`

`=8/13`

`d)-5/17 . (-9/23)+9/23 . (-22/17) + 11 9/23`

`=-5/17 . (-9/23) + 9/23 . (-1) . 22/17 + 11 + 9/23`

`=-5/17 . (-9/23) + (-9/23) . 22/17+11+9/23`

`= -9/23 ( -5/17 + 22/17)+11+9/23`

`= - 9/23 . 1+11+9/23`

`=-9/23+11+9/23`

`=(-9/23+9/23)+11`

`=0+11`

`=11`

a: =27/45-20/45=7/45

b: =3/5+30/40

=3/5+3/4

=12/20+15/20

=27/20

c: =8/13(7/2-5/2+1)=8/13*2=16/13

d: =9/23*5/17-9/23*22/17+11+9/23

=-9/23+11+9/23

=11

56666666

Bài 2 : 

a, \(x=\dfrac{3}{5}-\dfrac{7}{8}=\dfrac{24-30}{40}=-\dfrac{6}{40}=-\dfrac{3}{20}\)

b, \(2x-1=-2\Leftrightarrow x=-\dfrac{1}{2}\)

\(=\dfrac{9}{23}\left(\dfrac{5}{17}-\dfrac{22}{17}\right)+11+\dfrac{9}{23}=11\)