Answer:
[tex] \frac{r}{4} - 5[/tex]
Hope you could get an idea from here.
Doubt clarification - use comment section.
The expression till now
[tex]\\ \sf{:}\Rrightarrow \dfrac{r}{4}[/tex]
But we need the expression for five less than the quotient
[tex]\\ \sf{:}\Rrightarrow \dfrac{r}{4}-5[/tex]