Cześć!
1)
[tex]\frac{9}{4}=\frac{18}{x}\\\\9\cdot x=18\cdot4\\\\9x=72 \ \ /:9\\\\\huge\boxed{x=8}[/tex]
2)
[tex]\frac{11}{4}=\frac{9}{x}\\\\11\cdot x=9\cdot4\\\\11x=36 \ \ /:11\\\\\huge\boxed{x=\frac{36}{11}}[/tex]
3)
[tex]\frac{-1}{11}=\frac{2}{-x}\\\\-1\cdot(-x)=11\cdot2\\\\\huge\boxed{x=22}[/tex]
