Frictionless inclined plane problem

[Strelka]

Hi,
I am trying to finish my homework and I can't figure out one problem.
Can you help me, please?

A block (mass m1) lying on a frictionless inclined plane is connected to a mass m2 by a massless cord passing over a pulley.
a) Determine a formula for acceleration of the system of the two blocks in terms of m1, m2, alpha and g.
b) What conditions apply to masses m1 and m2 for the acceleration to be in one direction (say m1 down the plane), or in the opposite direction?

Thanks

[Sirus]

Please show us what you have tried so far and where you are stuck. Remember to always begin with a free-body diagram.