[tex]\\ \sf\longmapsto 5.9=\dfrac{x}{9}[/tex]
[tex]\\ \sf\longmapsto x=9(5.9)[/tex]
[tex]\\ \sf\longmapsto x=9(\dfrac{59}{100})[/tex]
[tex]\\ \sf\longmapsto x=53.1[/tex]
[tex]\sf \displaystyle \frac{x}{9} =5,9 \\\\x=9\cdot 5,9 =45+8,1=53,1 \\\\ \boxed{\sf x=53,1}[/tex]