Explanation:
Given that,
[tex]m=8-\dfrac{5}{r}[/tex]
(1) We need to find the value of r.
Subtract 8 from both sides,
[tex]m-8=8-8-\dfrac{5}{r}\\\\m-8=-\dfrac{5}{r}\\\\r(m-8)=-5\\\\r=\dfrac{-5}{(m-8)}[/tex]
So, the value of r is equal to [tex]\dfrac{-5}{(m-8)}[/tex].
(2) Put m=2 in the value of r. So,
[tex]r=\dfrac{-5}{(2-8)}\\\\r=\dfrac{5}{6}[/tex]
Hence, this is the required solution.