Answer :
[tex]\frac{z}{12}=6\frac{3}{4}\\\\\frac{z}{12}=\frac{6\times4+3}{4}\\\\\frac{z}{12}=\frac{27}{4}\ \ \ \ \ |multiply\ both\ sides\ by\ 12\\\\12\times\frac{z}{12}=12\times\frac{27}{4}\\\\z=3\times27\\\\\boxed{z=81}[/tex]
