Your question can be interpreted in two ways, I will solve both you then take the one you mean. Also there is no q in your equation, but I suppose you mean p.
[tex] \frac{6n-5p}{11t} =c \\ 6n-5p=11ct \\ 6n-11ct=5p \\ p= \frac{6n-11ct}{5} [/tex]
Alternatively,
[tex]6n-
\frac{5p}{11t} =c \\ 66nt-5p=11ct \\ 66nt-11ct=5p \\ p=
\frac{66nt-11ct}{5}[/tex]
