\(\dfrac{x}{5}=\dfrac{26}{65}\)

\(\Leftrightarrow65x=130\)

\(\Leftrightarrow x=2\)

\(\dfrac{3}{x}=\dfrac{51}{85}\)

\(\Leftrightarrow51x=255\)

\(\Leftrightarrow x=5\)

`x/5=26/65`

`65xx x=5xx26`

`65xx x=130`

`x=130:65=2`

`3/x=51/85`

`51xx x=3xx85`

`51xx x=255`

`x=255:51=5`

\(\dfrac{26x5}{65}=2\)

⇒ x = 2

\(\dfrac{85x3}{51}=5\)

⇒ x=5

\(a,\dfrac{x}{4}=\dfrac{15}{20}\\ \Rightarrow\dfrac{x}{4}=\dfrac{3}{4}\\ \Rightarrow x=3\\ b,\dfrac{15}{x}=\dfrac{25}{35}\\ \Rightarrow\dfrac{15}{x}=\dfrac{5}{7}\\ \Rightarrow\dfrac{15}{x}=\dfrac{15}{21}\\ \Rightarrow x=21\\ c,\dfrac{x}{5}=\dfrac{26}{65}\\ \Rightarrow\dfrac{x}{5}=\dfrac{2}{5}\\ \Rightarrow x=2\\ d,\dfrac{3}{x}=\dfrac{51}{85}\\ \Rightarrow\dfrac{3}{x}=\dfrac{3}{5}\\ \Rightarrow x=5\)

a,x4=1520⇒x4=34⇒x=3b,15x=2535⇒15x=57⇒15x=1521⇒x=21c,x5=2665⇒x5=25⇒x=2d,3x=5185⇒3x=35⇒x=5

51/85=39/65

15/21=25/35

\(\dfrac{51}{85}=\dfrac{39}{65}\)

\(\dfrac{15}{21}=\dfrac{25}{35}\)

a)  

\(\dfrac{1}{2}=0,5;\dfrac{3}{4}=0,75;\dfrac{7}{5}=1,4;\dfrac{9}{8}=1,125;\dfrac{26}{25}=1,04;\dfrac{120}{125}=0,96\)

b) 

\(\dfrac{15}{25}=0,6;\dfrac{75}{25}=3;\dfrac{90}{300}=0,3;\dfrac{27}{36}=0,75;\dfrac{51}{85}=0,6\)

a,1/2=5/10;3/4=75/100;7/5=140/100;26/25=108/100;120/125=960/1000

b,15/25=60/100;75/25=300/100;90/300=3/10;27/36=3/4=75/100;

51/85=3/5=60/100;39/65=3/5=60/100

a) 0,5; 0,75; 1,4; 1,125; 1,04; 0,96; 0,6

b) 0,6; 3,0; 0,3; 0,75; 0,6 

35 x 26 + 65 x 59 + 34 x 35 + 51 x 65

= 35 x ( 26 + 34 ) + 65 x ( 51 + 59 )

= 35 x 60 + 65 x 110

= 2100 + 7150

= 9250

   35 x 26 + 65 x 59 + 34 x 35 + 51 x 65

= 35 (26 + 34) + 65 (59 + 51)

= 35 x 60 + 65 x 110

= 2100 + 7150

= 9250

\(35x26+65x59+34x35+51x65=8791\)

\(K\)\(nha!!!\)

328185

507195

26/39=38/57

55/77=25/35

39/65=51/85

kb với mình nha

Ban oi trình bay cả cách làm nữa nhé 

26/39 = 38/57

55/77 = 25/35

39/65 = 51/85