Question

tìm x

Answer 1

`a, (36-x)/35 = 3/7`

`-> 36 - x = 15`

`x = 21`

`b, 3/4 = 15/x`

`-> x = 20`

Answer 2

b)\(\dfrac{36-x}{35}=\dfrac{9}{21}\)
\(\Leftrightarrow\)\(\left(36-x\right)\times21=35\times9\)
\(\Rightarrow\)\(\left(36-x\right)\times21=315\)
\(\Rightarrow\)\(36-x=315:21\)
\(\Rightarrow\)\(36-x=15\)
\(\Rightarrow\)        \(x=21\)

 

Answer 3

`(36-x)/35=9/21`

`(36-x)/35 =3/7`

`36-x=3/7 xx 35`

`36-x=105/7`

`36-x=15`

`x=36-15`

`x=21`

_______________________

`6/8 = 15/x`

`3/4 = 15/x`

`x=15:3/4`

`x=15 xx 4/3`

`x=20`

Vậy `x=20`

Answer 4

a)\(\dfrac{6}{8}=\dfrac{15}{x}\Rightarrow6\times x=15\times8\)
                 \(\Rightarrow\)\(6\times x=120\Rightarrow x=120:6\)
                 \(\Rightarrow x=20\)