Answer :
[tex]\frac{\frac{4a}{b}}{\frac{2ac}{b}}=?\\\\
To\ divide\ fraction\ multiply\ first\ fraction\ by\ inverse\ of\ the\ second:\\\\
\frac{\frac{4a}{b}}{\frac{2ac}{b}}=\frac{4a}{b}*\frac{b}{2ac}=?\\\\
Shortening\ fractions:\\\\
\frac{\frac{4a}{b}}{\frac{2ac}{b}}=\frac{4a}{b}*\frac{b}{2ac}=\frac{2}{c}\\\\Solution\ is\ \frac{2}{c}.[/tex]
[tex]\frac{4a}{b} :\frac{ 2ac}{b}= \frac{4a}{b} \cdot \frac{b}{ 2ac}= \frac{2}{c} \\ \\a \ and \ c \neq 0[/tex]