\(\frac{25-x}{56}=\frac{6}{16}\)

\(\Rightarrow\frac{25-x}{56}=\frac{3}{8}\)

\(\Rightarrow\left(25-x\right).8=56.3\)

\(\Rightarrow25.8-8x=168\)

\(\Rightarrow200-8x=168\)

\(\Rightarrow8x=200-168\)

\(\Rightarrow8x=32\)

\(\Rightarrow x=32:8\)

\(\Rightarrow x=4\)

Tham khảo nha !!! 

Cách này dễ hơn nèk : 

\(\frac{25-x}{56}=\frac{6}{16}\)

\(\Leftrightarrow\)\(\frac{25-x}{56}=\frac{3}{8}\)

\(\Leftrightarrow\)\(\frac{25-x}{56}=\frac{21}{56}\)

\(\Leftrightarrow\)\(25-x=21\)

\(\Leftrightarrow\)\(x=25-21\)

\(\Leftrightarrow\)\(x=4\)

Vậy \(x=4\)

Chúc bạn học tốt ~ 

\(\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{4}\right)+\left(x+\frac{1}{8}\right)+\left(x+\frac{1}{16}\right)=1\)

\(x\cdot4+\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)=1\)

\(x\cdot4+\left(\frac{8}{16}+\frac{4}{16}+\frac{2}{16}+\frac{1}{16}\right)=1\)

\(x\cdot4+\frac{13}{16}=1\)

\(x\cdot4=1-\frac{13}{16}\)

\(x\cdot4=\frac{3}{16}\)

      \(x=\frac{3}{16}:4\)

      \(x=\frac{3}{64}\)

\(\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{4}\right)+\left(x+\frac{1}{8}\right)+\left(x+\frac{1}{16}\right)=1\)

\(=\left(x+x+x+x\right)+\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)=1\)

\(=4x+\frac{15}{16}=1\)

\(\Rightarrow4x=1-\frac{15}{16}=\frac{1}{16}\)

\(\Rightarrow x=\frac{1}{16}:4=\frac{1}{64}\)

a, X = 1.                                                 b, X = 17.                             ĐOÁN LÁO THÔI HÌ.

12:3=4x2=8-7=1

a/x=1

16:2=8x1=25-8=17

b/x=17 tick nha

\(\frac{2}{5}\)x m + 25% x m + m = 16,5

m x ( \(\frac{2}{5}\) + 25% + 1 ) = 16,5

m x \(\frac{33}{20}\)= 16,5

m = 16,5 : \(\frac{33}{20}\)

m = 10

\(\frac{24}{400}+50\%+\frac{3}{100}+25\%\)

\(=0,24\%+50\%+0,03\%+25\%\)

\(=50,52\%\)

a) \(\frac{x}{y}.\frac{3}{7}=\frac{4}{9}\)

\(\frac{x}{y}=\frac{4}{9}:\frac{3}{7}\)

\(\frac{x}{y}=\frac{4}{9}.\frac{7}{3}\)

\(\frac{x}{y}=\frac{28}{27}\)

a)\(\frac{x}{17}=\frac{60}{204}=\frac{5}{17}\Rightarrow x=5\)

b)\(\frac{6+x}{33}=\frac{7}{11}\Rightarrow11\left(6+x\right)=7.33\Rightarrow11.6+11x=231\Rightarrow66+11x=231\)

\(\Rightarrow11x=231-66\Rightarrow11x=165\Rightarrow x=\frac{165}{11}=15\)

c)\(\frac{12+x}{43-x}=\frac{2}{3}\Rightarrow2\left(43-x\right)=3\left(12+x\right)\Rightarrow2.43-2x=3.12+3x\)

\(86-2x=36+3x\Rightarrow86-36=3x+2x\Rightarrow50=5x\Rightarrow x=\frac{50}{5}=10\)

a) \(\frac{x-2}{255}=\frac{114}{153}\)

\(\Leftrightarrow\left(x-2\right)\cdot153=114\cdot255\)

\(\Leftrightarrow\left(x-2\right)\cdot153=29070\)

\(\Leftrightarrow x-2=190\)

\(\Leftrightarrow x=192\)

b) \(\frac{50}{19}\cdot\frac{38}{25}\le x\le\frac{69}{17}+\frac{33}{17}\)

\(\Leftrightarrow4\le x\le6\)

Vậy x =4 hoặc x=5 hoặc x=6

Ta có : \(\frac{1}{4}+\frac{1}{3}:\frac{1}{x}=\frac{11}{12}\)

\(\Rightarrow\frac{1}{3}:\frac{1}{x}=\frac{11}{12}-\frac{1}{4}\)

\(\frac{1}{3}:\frac{1}{x}=\frac{2}{3}\)

\(\frac{1}{x}=\frac{1}{3}:\frac{2}{3}\)

\(\frac{1}{x}=\frac{1}{3}\times\frac{3}{2}\)

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

=> x = 2

a) \(\frac{x\div3-16}{2}+21=38\)

\(\frac{x\div3-16}{2}=38+21\)

\(\frac{x\div3-16}{2}=59\)

\(x\div3-16=59.2\)

\(x\div3-16=118\)

\(x\div3=118+16\)

\(x\div3=134\)

\(x=134.3\)

\(x=402\)

b) \(\frac{1}{4}+\frac{1}{3}\div\frac{1}{x}=\frac{11}{12}\)

\(\frac{1}{3}\div\frac{1}{x}=\frac{11}{12}-\frac{1}{4}\)

\(\frac{1}{3}\div\frac{1}{x}=\frac{2}{3}\)

\(\frac{1}{x}=\frac{1}{3}\div\frac{2}{3}\)

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

Vậy x = ....