x:10+x*9,9=30,25

x*0,1+x*9.9=30,25

x*(0,1+9,9)=30,25

x*10=30,25

x=30.25:10=3,025

x=3.025

tích nha !

\(x:100+x.0,99=5,25\)

\(\Leftrightarrow x.\frac{1}{100}+x.\frac{99}{100}=\frac{21}{4}\)

\(\Leftrightarrow x.\left(\frac{1}{100}+\frac{99}{100}\right)=\frac{21}{4}\)

\(\Leftrightarrow x.1=\frac{21}{4}\)

\(\Leftrightarrow x=\frac{21}{4}\)

\(x\times0,99+x:100=2019\\ \Rightarrow x\times0,99+x\times0,01=2019\\ \Rightarrow x\times\left(0,99+0,01\right)=2019\\ \Rightarrow x\times1=2019\\ \Rightarrow x=2019\)

\(x\times9,9+x:10=20,06\\ \Rightarrow x\times9,9+x\times0,1=20,06\\ \Rightarrow x\times\left(9,9+0,1\right)=20,06\\ \Rightarrow x\times10=20,06\\ \Rightarrow x=20,06:10\\ \Rightarrow x=2,006\)

nhớ nhau ko

a/ => x.9,9 + x . 1/10 = 20,06

=> x(9,9 + 1/10) = 20,06

=> x  = 2,006

b/ => x.100,01 - x.1/100 = 35,5

=> x(100,01 - 1/100) = 35,5

=> x = 0,355