Ta có: \(\left(x-5\right)\frac{30}{100}=\frac{20x}{100}+5\)

\(\Rightarrow\left(x-5\right)\frac{3}{10}=\frac{x}{5}+5\)

\(\Rightarrow\frac{3x-15}{10}=\frac{25+x}{5}\)

\(\Rightarrow5\left(3x-15\right)=10\left(25+x\right)\)

\(\Rightarrow15x-75=250+10x\)

\(\Rightarrow15x-10x=250+75\)

\(\Rightarrow5x=325\Rightarrow x=\frac{325}{5}=65\)

\(\left(x-8\right).\frac{3}{10}=\frac{1}{5}x+5\)

\(\frac{3}{10}x-\frac{3}{2}=\frac{1}{5}x+5\)

\(\frac{3}{10}x=\frac{1}{5}x+6,5\)

\(\Rightarrow\frac{1}{10}x=6,5\)

\(x=\frac{6,5}{\frac{1}{10}}\)

\(x=65\)

Vậy \(x=65\)

\(\left(x-5\right).\frac{30}{100}=\frac{20x}{100}+5\)

\(\Leftrightarrow\left(x-5\right).0,3=0,2.x+5\)

\(\Leftrightarrow0,3.x-1,5=0,2.x+5\)

\(\Leftrightarrow0,3.x-0,2.x=5+1,5\)

\(\Leftrightarrow0,1.x=6,5\)

\(\Leftrightarrow x=65\)

\(\frac{\left(x-5\right).30}{100}=\frac{20x}{100}+\frac{500}{100}\)

\(\frac{30x-150}{100}=\frac{20x+500}{100}\)

=> 30x - 150 = 20x + 500

30x - 20x = 500 + 150

10x = 650

x = 65

a)x=30

b)x=65

a) x-\(\left(\frac{50x}{100}+\frac{25x}{200}\right)\)=\(11\frac{1}{4}\)

<=>x - \(\frac{1}{2}x-\frac{1}{8}x\)=\(\frac{11.4+1}{4}\)

<=>\(\frac{3}{8}x=\frac{45}{4}\)

<=>x=\(\frac{45}{4}:\frac{3}{8}\)

<=>x=30

Vậy x=30

c) (x-5).\(\frac{30}{100}\)=\(\frac{20x}{100}+5\)

<=>(x-5).\(\frac{3}{10}\)=\(\frac{x}{5}\)+5

<=>\(\frac{3x}{10}-\frac{15}{10}=\frac{x}{5}+5\)

<=>\(\frac{3x}{10}-\frac{x}{5}=5+\frac{15}{10}\)

<=>\(\frac{x}{10}=\frac{13}{2}\)

<=>x=\(\frac{13.10}{2}\)

<=>x=65

Vậy: x=65

(x - 5).30/100 = 20x/100 + 5 
<=>30x-150=20x+500 (quy đồng 2 vế rồi khử mẫu) 
<=>10x=650 
<=>x=65 

Ta có thể viết thành: (x - 5)3/10 = x/5 + 5

Nhân hai vế với 10, ta có : 3(x - 5) = (x/5 + 5) * 10

                                           3x - 15 = 2x + 50

                                           3x = 2x + 50 = 2x + 65

                                           3x - 2x = 65

                                           x = 65

Chúc bạn ht ~~