\(\dfrac{18}{31}\times\dfrac{62}{9}\)

\(=\dfrac{18\times62}{31\times9}\)

\(=\dfrac{2\times2}{1}\)

\(=4\)

==============

\(\dfrac{35}{72}\times\dfrac{63}{20}\)

\(=\dfrac{35\times63}{72\times20}\)

\(=\dfrac{7\times7}{8\times4}\)

\(=\dfrac{49}{32}\)

===============

\(\dfrac{34}{65}:\dfrac{17}{15}\)

\(=\dfrac{34}{65}\times\dfrac{15}{17}\)

\(=\dfrac{34\times15}{65\times17}\)

\(=\dfrac{2\times3}{13\times1}\)

\(=\dfrac{6}{13}\)

===========

\(\dfrac{111}{64}:\dfrac{37}{40}\)

\(=\dfrac{111}{64}\times\dfrac{40}{37}\)

\(=\dfrac{111\times40}{64\times37}\)

\(=\dfrac{3\times5}{8\times1}\)

\(=\dfrac{15}{8}\)

=============

\(\dfrac{12}{19}\times\dfrac{41}{52}:\dfrac{82}{19}\)

\(=\dfrac{12}{19}\times\dfrac{41}{52}\times\dfrac{19}{82}\)

\(=\dfrac{12\times41\times19}{19\times52\times82}\)

\(=\dfrac{3\times1\times1}{1\times13\times2}\)

\(=\dfrac{3}{26}\)

\(\frac{21.19+19.79}{38.50}\)

\(=\frac{19.\left(21+79\right)}{38.50}\)

\(=\frac{19.100}{38.50}\)

\(=\frac{19.2.50}{19.2.50}\)

\(=1\)

21 × 19 + 19 × 79 / 38 × 50

= 21 × 19 + 0,79

= ( 20 + 1 ) ×  19 + 0,79

= 20 × 19 + 1 × 19 + 0,79

= 380 + 19 + 0,79

= 399 + 0,79

= 399,79

\(\frac{21\cdot19+19\cdot79}{38\cdot50}\)

\(=\frac{19\left(21+79\right)}{38\cdot50}\)

\(=\frac{19\cdot100}{38\cdot50}\)

\(=\frac{19\cdot50\cdot2}{19\cdot2\cdot50}=1\)

3,6 \(\times\) 62 + 7,2 \(\times\) 19 + 7,2 \(\times\) 50

= 3,6 \(\times\) 2 \(\times\) 31 + 7,2 \(\times\) 19 + 7,2 \(\times\) 50

= 7,2 \(\times\) 31 + 7,2 \(\times\) 19 + 7,2 \(\times\) 50

= 7,2 \(\times\) ( 31 + 19 + 50)

= 7,2 \(\times\) 100

= 720

\(\dfrac{54\times50+49\times100}{37\times38+126\times19}\)

\(=\dfrac{50\times\left(49\times2+54\right)}{38\times\left(63+37\right)}\)

\(=\dfrac{50\times152}{38\times100}\)

\(=\dfrac{25\times2\times4\times38}{38\times25\times4}\)

\(=2\)

19 + ( x - 23 ) = 50 

x - 23 = 50 - 19 

x - 23 = 31 

x = 31 + 23 

x = 54 

nha bn

19+(x-23)=50

x-23=50-19

x-23=31

x=31+23

x=54

=>x-23=50-19

=>x-23=31

=>x=31-29

=>x=2

tíc mình nha

a) x+19=29

   x       = 29 - 19

   x       = 10

Vậy x = 10

b)x-37=50

  x      = 50 + 37

 x       = 87

Vậy x = 87

# HOK TỐT #

\(\text{a) x+19=29}\)

\(x=29-19\)

\(x=10\)

\(\text{b)x-37=50}\)

\(x=50+37\)

\(x=87\)

học tốt

a) x+19=29
    x      =29-19
    x      =10          
b) x-37=50
    x     =50+37
    x     =87
HỌC TỐT

450:(x-19)=50

=> x-19=450:50

=> x-19=9

=> x=9+19

Vậy x=28.

450:(x-19)=50

x-19=450:50

x-19=9

x=19+9

x=28

x=28

HOK TOT

(19-x)=-11-50

(19-x)=-61

x=19--61

x=80

-11-(19-x)=50

=> -11 -19+x=50

=> -30+x=50

x=-30-50

x=-80

k cho mh nha

mh trả lời đầu tiên

-11-(19-x)=50

          19-x=(-11)-50

          19-x=-61

                x=19-(-61)

                x=80

\(a.13.\left(78+22\right)=13.100=1300\)

\(b.25.70+28.25+25.2=25.\left(70+28+2\right)=25.100=2500\)

\(c.\dfrac{15.3.14.2.19}{19.14.15}=6\)

\(d.\dfrac{132.70.60}{12.35.20}=\dfrac{11.12.35.2.20.3}{12.35.20}=66\)