please help me .... Thank you

[tex]\\ \sf\longmapsto \dfrac{4}{6x+2}[/tex]
[tex]\\ \sf\longmapsto \dfrac{5x+3y}{16-8y}[/tex]
[tex]\\ \sf\longmapsto \dfrac{2}{4x-3}[/tex]
[tex]\\ \sf\longmapsto \dfrac{2ab+c^2}{3n-2m}[/tex]
[tex]\\ \sf\longmapsto \dfrac{a^2-16}{7x}[/tex]