bạn viết lại đầu bài đi. Viết thế ai biết gì mà giải chứ

a) \(\left(\dfrac{1}{4}x\right):3=\dfrac{5}{6}:\dfrac{1}{8}\\ \left(\dfrac{1}{4}x\right):3=\dfrac{20}{3}\\ \dfrac{1}{4}x=\dfrac{20.3}{3}\\ \dfrac{1}{4}x=20\\ x=80\)

a: Ta có: \(\dfrac{0.25x}{3}=\dfrac{5.6}{0.125}\)

\(\Leftrightarrow x\cdot\dfrac{1}{4}=134.4\)

hay x=537,6

b: Ta có: \(\dfrac{2.5}{7.5}=x:\dfrac{3}{5}\)

\(\Leftrightarrow x:\dfrac{3}{5}=\dfrac{1}{3}\)

hay \(x=\dfrac{1}{5}\)

\(\dfrac{5}{2}:\dfrac{15}{2}=x:\dfrac{7}{5}\\ x:\dfrac{7}{5}=\dfrac{1}{3}\\ x=\dfrac{7}{15}\)

\(\frac{37-x}{x+13}=\frac{3}{7}\)

\(\Leftrightarrow\left(37-x\right)7=\left(x+13\right)3\)

\(\Leftrightarrow259-7x=3x+39\)

\(\Leftrightarrow-7x-3x=39-259\)

\(\Leftrightarrow-10x=-220\)

\(\Rightarrow x=\frac{-220}{-10}=22\)

Vậy x =22

a)\(\frac{x-1}{x+2}=\frac{x-2}{x+3}\Rightarrow\left(x-1\right)\left(x+3\right)=\left(x+2\right)\left(x-2\right)\)

\(\Rightarrow x^2+2x-3=x^2-4\)

\(\Rightarrow2x=-1\)

\(\Rightarrow x=-\frac{1}{2}\)

b)\(\frac{37-x}{x+13}=\frac{3}{7}\)\(\Rightarrow7\left(37-x\right)=3\left(x+13\right)\)

\(\Rightarrow259-7x=3x+39\)

\(\Rightarrow10x=220\)

\(\Rightarrow x=22\)

a,  0,4 : x = x : 0,9

<=> x² = 0,4 . 0,9

<=> x² = 0,36

<=> x = 0,6 hoặc -0,6

b, \(13\frac{1}{3}\div1\frac{1}{3}=26\div\left(2x-1\right)\)

\(\Leftrightarrow\frac{40}{3}\div\frac{4}{3}=26\div\left(2x-1\right)\)

\(\Leftrightarrow10=26\div\left(2x-1\right)\)

\(\Leftrightarrow2x-1=\frac{13}{5}\)

\(\Leftrightarrow2x=\frac{18}{5}\)

\(\Leftrightarrow x=\frac{9}{5}\)

c, \(0,2\div1\frac{1}{5}=\frac{2}{3}\div\left(6x+7\right)\)

\(\Leftrightarrow\frac{1}{5}\div\frac{6}{5}=\frac{2}{3}\div\left(6x+7\right)\)

\(\Leftrightarrow\frac{1}{6}=\frac{2}{3}\div\left(6x+7\right)\)

\(\Leftrightarrow6x+7=4\)

\(\Leftrightarrow6x=-3\)

\(\Leftrightarrow x=\frac{-1}{2}\)

d, \(\frac{37-x}{x+13}=\frac{3}{7}\) 

\(\Leftrightarrow7\left(37-x\right)=3\left(x+13\right)\)

\(\Leftrightarrow259-7x=3x+39\)

\(\Leftrightarrow-10x=-220\)

\(\Leftrightarrow x=22\)

\(\text{a)}\frac{37-x}{x+13}=\frac{3}{7}\)

\(\Leftrightarrow3\left(x+13\right)=7\left(37-x\right)\)

\(\Leftrightarrow3x+39=259-7x\)

\(\Leftrightarrow3x+7x=259-39\)

\(\Leftrightarrow10x=220\)

\(\Leftrightarrow x=22\)

\(\text{b)}\frac{x+4}{20}=\frac{5}{x+4}\)

\(\Leftrightarrow\left(x+4\right)^2=100\)

\(\Leftrightarrow\orbr{\begin{cases}x+4=10\\x+4=-10\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=6\\x=-14\end{cases}}\)

tìm x trong tỉ lệ thức sau x/64=-3/0.8;20/17=x/81