Answer:
[tex]\huge\boxed{r=\dfrac{57}{5}\to r=11\dfrac{2}{5}\to r=11.4}[/tex]
Step-by-step explanation:
[tex]19=\dfrac{5}{3}r\to\dfrac{5}{3}r=19\qquad|\text{multiply both sides by 3}\\\\3\!\!\!\!\diagup\cdot\dfrac{5}{3\!\!\!\!\diagup}r=19\cdot3\\\\5r=57\qquad|\text{divide both sides by 5}\\\\\dfrac{5r}{5}=\dfrac{57}{5}\\\\r=\dfrac{57}{5}\to r=11\dfrac{2}{5}\to r=11.4[/tex]
