`x : 5/2 = 7/3`

`=> x= 7/3 xx 5/2`

`=>x= 35/6`

__

`23,7 xx 49 +23,7 xx 51`

`= 23,7 xx (49+51)`

`= 23,7 xx 100`

`=2370`

Lời giải:
a. 

$x=\frac{7}{3}\times \frac{5}{2}=\frac{35}{6}$

b.

$23,7\times 49+23,7\times 51=23,7\times (49+51)=23,7\times 100=2370$

x: 5/2=7/3`

`=> x = 7/3 xx 5/2`

`=> x=35/6`

Vậy `x = 35/6`

`23,7 xx 49 + 23,7 xx 51`

` =23,7 xx(49+51)`

`= 23,7 xx 100`

`=2370`

\(5\dfrac{3}{4}:3+2\dfrac{1}{4}\times\dfrac{1}{3}-\dfrac{1}{8}=\left(5\dfrac{3}{4}+2\dfrac{1}{4}\right)\times\dfrac{1}{3}-\dfrac{1}{8}\\ =8\times\dfrac{1}{3}-\dfrac{1}{8}=\dfrac{8}{3}-\dfrac{1}{8}=\dfrac{61}{24}\\ ----\\ \dfrac{3}{5}:\dfrac{5}{6}:\dfrac{6}{7}:\dfrac{7}{8}+\dfrac{2}{5}+\dfrac{23}{35}\\ =\dfrac{3}{5}\times\dfrac{6}{5}\times\dfrac{7}{6}\times\dfrac{8}{7}+\dfrac{2}{5}+\dfrac{23}{35}=\dfrac{18}{25}\times\dfrac{4}{3}+\dfrac{2}{5}+\dfrac{23}{35}=\dfrac{353}{175}\)

=11/6*(15/23-7/23)
=11/6*8/23
=44/69
chúc bn hk tốt

\(\frac{11}{6}\times\frac{15}{23}-\frac{11}{6}\times\frac{7}{23}\)=  \(\frac{11}{6}\times\left(\frac{15}{23}-\frac{7}{23}\right)\)

                                                       =\(\frac{11}{6}\times\frac{8}{23}\)

                                                       =  \(\frac{44}{69}\)

c bn

chúc bạn học tốt

TL:

a)25 x 12 x 30 x 4 

= (25 x 5) x (12 x 30)

= 100 x 360

= 36000

b)23 + 23 x 2 + 23 x 3 +23 x 4 

= 23 x 1 + 23 x 2 + 23 x 3 +23 x 4

= 23 x (1 + 2 + 3 + 4)

= 23 x 10

= 230

c)248 x 2005 - 2005 x 148

= (248 - 148) x 2005

= 100 x 2005

= 200500

HT

a) 25 x 12 x 30 x 4

= (25x4)x(12x30)

=100x360

=36000

b)23+23x2+23x3+23x4

= 23x1+23x2+23x3+23x4

=23x(1+2+3+4)

=23x10

=230

c)248x2005-2005x148

=2005x(248-148)

=2005x100

=100500

Chúc bạn học tốt nhé!

nhiều thế

sfdhg 

567 x 23 + 433 x 23 = 23 x (567 + 433)

                                 =23 x 1000 = 23 000

a, 25+35+76+65+22
=(65+35)+(76+22)+25
=100+100+25
=225
c , 78-23-25
=78-(23+25)
=78-48
=30
a , x-45=20 
x=20+45
x=65
b , 45 - x=20
     x =45-20
     x= 25

Bài 2: 

a: Ta có: x-45=20

nên x=65

b: Ta có: 45-x=20

nên x=25

TL: 

8/15 x 5/6 = 40/90 = 4/9 

41/20 x 3/4 = 123/80 

(11/23 + 9/23) + (18/23 + 2/23) = 20/23 + 20/23 = 40/43 

HT

\(\left(\frac{2}{3}\times\frac{4}{5}\right)\times\frac{5}{6}\) = \(\frac{2}{3}\times\frac{4}{5}\times\frac{5}{6}\)=\(\frac{2\times4\times5}{3\times5\times6}\)=\(\frac{2\times4\times5}{3\times5\times2\times3}\)=\(\frac{4}{9}\)

\(\frac{11}{23}+\frac{2}{23}+\frac{9}{23}+\frac{18}{23}\)=\(\frac{\left(11+9\right)+\left(18+2\right)}{23}\)=\(\frac{20+20}{23}\)=\(\frac{40}{23}\)

\(\frac{27}{12}+\frac{17}{6}-\frac{25}{36}-\frac{15}{6}\)=\(\left(\frac{27}{12}-\frac{25}{36}\right)+\left(\frac{17}{6}-\frac{15}{6}\right)\)=\(\frac{14}{9}+\frac{2}{6}\)=\(\frac{17}{9}\)

/HT\

Nhập các bạn toàn bắt tớ làm à ngu gò mà làm

( 20,33 + 35,12) x 33 – 45,45 x 23 – 10 x 23

            = 55,45 x 33    -    (45,45 + 10) x 23

            =  55,45  x 33  -          55,45     x 77

            =  55,45  x   ( 33  - 23)

            =  55, 45 x 10  =  554,5