Consider the following image:

I am trying to determine the acceleration of this system. $/mu = 0.20$ and $ m = 4 kg$.

Would I be correct using:

$T = m \cdot a + F_{f}$ and $ Bg - (F_{f} - T) = Ba$

With B denoting the mass of object B?

I'm not sure where to proceed from here. I want to try and combine these but I'm having trouble doing so.