Find the linear acceleration of weight A with a mass of [a]k…

Find the linear acceleration of weight A with a mass of [a]kg.  It is connected by a light cable over a frictionless pulley to the center of thin circular disk B (I at center is ½*m*r2) with a mass of [b]kg, radius of [r]m.  Disk B rolls without slipping.  Use g=10m/s2 to simplify the calculations.  Answer in m/s2 with up positive.