Answer :
[tex]\frac{1}{4}+\frac{4}{5}x=\frac{11}{20}\\\\\frac{4}{5}x=\frac{11}{20}-\frac{1}{4}\\\\\frac{4}{5}x=\frac{11}{20}-\frac{5}{20}\\\\\frac{4}{5}x=\frac{6}{20}\ \ \ \ \ \ \ |\cdot\frac{5}{4}\\\\x=\frac{30}{80}=\frac{3}{8}[/tex]
