`450 xx 0,45+ 1,5 xx 30 xx 3 + 5 xx 9 xx 2,5`

`= 45 xx10 xx 0,45  + 45 xx 3 + 45xx2,5`

`= 45 xx 4,5 + 45 xx 3 + 45 xx 2,5`

`= 45 xx ( 4,5 + 3 +2,5)`

`= 45 xx 10`

`=450`

     \(\dfrac{45}{100}+\dfrac{9}{20}\times29+45\%\times30\) + 0,9 \(\times\) 20

=    \(\dfrac{9}{20}\) + \(\dfrac{9}{20}\times29\) + \(\dfrac{9}{20}\) \(\times\) 30 + 18

= \(\dfrac{9}{20}\) \(\times\) ( 1 + 29 + 30) + 18

= \(\dfrac{9}{20}\) \(\times\) 60 + 18

= 27 + 18

= 45

lỗi rồi

lỗi

a,

=85.35-85.27-35.85+35.27

=85.35+85.(-27)-35.85+35.27

=85[35+(-27)+(-35)]+35.27

=85.(-27)+35.27

=-85.27+35.27

=27.[(-85)+35]

=27.(-50)

=-1350

các câu còn lại cũng vậy

a, 85 x ( 35- 27 ) - 35 x ( 35 - 27 )

85 x 8 - 35 x 8

8 x ( 85 - 35 ) 

8 x 50 = 400

b, ( -45 ) x 69 + 30 x ( -45 ) +( -45)

( -45 ) x ( 69 + 30 + 1)

-45 x 100 = -4500

c , 26 + 7 x ( 4 - 12 )

26 + 7 x ( - 8 )

26 + ( -56 )=(- 30)

d , 127 - 18 x ( 5 + 6 )

127 - 18 x 11

127 - 180 + 18

-53 + 18 = - 35

\(a,45-\left(30+x\right)=x-\left(37-8\right)\)

\(\Leftrightarrow45-30-x=x-37+8\)

\(\Leftrightarrow-x-x=-37+8-45+30\)

\(\Leftrightarrow-2x=-44\)

\(\Leftrightarrow x=22\)

\(b,\left(x-12\right)-15=\left(30-8\right)-\left(40+x\right)\)

\(\Leftrightarrow x-12-15=30-8-40-x\)

\(\Leftrightarrow x+x=30-8-40+12+15\)

\(\Leftrightarrow2x=9\)

\(\Leftrightarrow x=4,5\)

45-(30+x)=x-(27-48)

45-30-x=x-27+48

-x-x=-27+48+20-45

-2x=-4

x=(-4):(-2)=2

Chuyển vế rồi tìm x bạn ạ 

tích mk là may cả năm

=> 45-30-x=x-27+48

=> 15-x= x+21

=> 15-x+x=x+21+x

=> 15= 2x+21

=> 2x=15-21

=> 2x=(-6)

=> x=(-6):2

=> x= (-3)

\(45\cdot y-30=12\cdot15-40\cdot3\)

\(\Rightarrow45\cdot y-30=180-120\)

\(\Rightarrow45\cdot y-30=60\)

\(\Rightarrow45\cdot y=60+30\)

\(\Rightarrow45\cdot y=90\)

\(\Rightarrow y=90:45\)

\(\Rightarrow y=2\)

\(\Leftrightarrow45y-30=60\Leftrightarrow45y=90\Leftrightarrow y=2\)