The remainder can be defined for all real numbers $x$ and $y$ with $y\ne 0$ by
$\mathrm{rem}(x,y)=x-y\lfloor \frac{x}{y}\rfloor$
where $\lfloor \frac{x}{y}\rfloor$ denotes the greatest integer less than or equal to $\frac{x}{y}$. What is the value of $\mathrm{rem}\left(-\frac{5}{6},\frac{3}{4}\right)$?