Let f(x)=9sinx/2sinx+4cosx.

Question

Then 'f(x)= ((2sinx+4cosx)(9cosx)-(9sinx)(2cosx-4sinx))/(2sinx+4cosx)^2.
The equation of the tangent line to y=f(x) at a=2 can be written in the form y=mx+b where
m= 9and
b= ______.?????