[tex]\frac{20x}{100}=\frac{30y}{100}+4\\
\frac{x}{5}=\frac{3y}{10}+4\\
2x=3y+40\\
\frac{x+y}{x-y}=\frac{5}{6}=\ \textgreater \ 5x-5y=6x+6y\\
-x=11y\\
x=-11y\\
Inlocuim:\\
-22y=3y+40\\
-25y=40\\
y=\frac{-40}{25}=-\frac{8}{5}\\
x=-11*\frac{-8}{5}=\frac{88}{5}
[/tex]