(Xx1)+(Xx2)+(Xx3)+(Xx4)=50

=>4xX+10=50

=>4xX=50-10

=>4xX=40

=>X=40:10

=>X=4

X x 2+X x 1/6 =8/5

=> X x (2+1/6)=8/5

=> X x 13/6=8/5

 =>         X  =8/5:13/6

=>         X   =48/65

\(x\times2+x\times\dfrac{1}{6}=\dfrac{8}{5}\)

\(\Leftrightarrow2x\times2\times\dfrac{1}{6}=\dfrac{8}{5}\)

\(\Leftrightarrow2x\times\dfrac{1}{3}=\dfrac{8}{5}\)

\(\Leftrightarrow2x=\dfrac{8}{5}:\dfrac{1}{3}\)

\(\Leftrightarrow2x=\dfrac{8}{5}\times\dfrac{3}{1}\)

\(\Leftrightarrow2x=\dfrac{24}{5}\)

\(\Leftrightarrow x=\dfrac{24}{5}:2\)

\(\Leftrightarrow x=\dfrac{24}{5}\times\dfrac{1}{2}\)

\(\Leftrightarrow x=\dfrac{24}{10}\)

\(\Leftrightarrow x=\dfrac{12}{5}\)

sửa hộ chỗ nay thành này nha mình bấm nhanh quá nên hơi lỗi

` x xx 1/3 : 2/5 =4/3`

`=> x xx 1/3 = 4/3 xx 2/5`

`=> x xx 1/3 = 8/15`

`=> x= 8/15 :1/3`

`=> x= 8/15 xx 3`

`=> x= 24/15`

`=> x= 8/5`

=>11/10x=11/15

hay x=3/2

\(x+x\times\frac{1}{4}\div\frac{2}{7}+x\div\frac{2}{9}=255\)

\(\Rightarrow x+x\times\frac{1}{4}\times\frac{7}{2}+x\times\frac{9}{2}=255\)

\(\Rightarrow x+x\times\frac{7}{8}+x\times\frac{9}{2}=255\)

\(\Rightarrow x.\left(1+\frac{7}{8}+\frac{9}{2}\right)=255\)

\(\Rightarrow x\cdot\frac{51}{8}=255\)

\(\Rightarrow x=255\div\frac{51}{8}\)

\(\Rightarrow x=255\times\frac{8}{51}\)

\(\Rightarrow x=40\)

Vậy x = 40 

a)\(x+\dfrac{2}{3}x\dfrac{5}{6}=7\)

\(x+\dfrac{10}{18}=7\)

\(x=7-\dfrac{10}{18}\)

\(x=\dfrac{58}{9}\)

b)\(9-xx\dfrac{1}{2}=\dfrac{3}{4}\)

\(xx\dfrac{1}{2}=9-\dfrac{3}{4}\)

\(xx\dfrac{1}{2}=\dfrac{33}{4}\)

\(x=\dfrac{33}{4}:\dfrac{1}{2}\)

\(x=\dfrac{33}{2}\)

c)\(18-x:\dfrac{2}{3}=\dfrac{4}{5}-\dfrac{1}{10}\)

\(18-x:\dfrac{2}{3}=\dfrac{7}{10}\)

\(x:\dfrac{2}{3}=18-\dfrac{7}{10}\)

\(x:\dfrac{2}{3}=\dfrac{173}{10}\)

\(x=\dfrac{173}{10}x\dfrac{2}{3}\)

\(x=\dfrac{173}{15}\)

1+1+1+1+1+1+2+5+10+4+7=34

(1+9)+(2+8)+(3+7)+(4+6)+(5+5)+(10+0)

=10+10+10+10+10+10

=10x6

=60

Xx1+3=7

X+3=7x1

X+3=7

     X=7-3

     X=4

(x+x+x+...+x)+(1+4+7+10+...+28)=315

Số số hạng trong ngoặc đơn là

(28-1):3+1=10 số hạng

=> 10*x+10*(28+1):2=315

10*x=170 => x=17

(x+x+x+...+x)+(1+4+7+10+...+28)=315

Số số hạng trong ngoặc đơn là

(28-1):3+1=10 số hạng

=> 10*x+10*(28+1):2=315

10*x=170 => x=17

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x*1,2+x*1,8=45

x*(1,2+1,8)=45

x* 3=45

x= 45:3

x=15

k dung cho mik nha!>-<