Question

 

 

40%.x +55%.x =20%

Answer 1

40%.x+55%.x=20%

<=>\(\frac{2}{5}.x+\frac{11}{20}.x=\frac{1}{5}\)

<=>\(x\left(\frac{2}{5}+\frac{11}{20}\right)=\frac{1}{5}\)

<=>\(x\frac{19}{20}=\frac{1}{5}\)

<=>\(x=\frac{4}{19}\)

Vậy \(x=\frac{4}{19}\)

Answer 2

40%.x+55%.x=20%

x.(40%+55%)=20%

x.95%          =20%

x                 =20% - 95%

x                 =-3/4