Bonjour,
[tex] \frac{2}{3} + r = \frac{10}{3} [/tex]
[tex] \frac{2}{3} + r - \frac{2}{3} = \frac{10}{3} - \frac{2}{3} [/tex]
[tex]\boxed{r= \frac{8}{3} }[/tex]
