Part A.
To get the acceleration of the system we consider the two blocks as a single mass. For this situation we have, from Newton's second law, that:
where T is the tension in the upper sting and W is the weight of the system. Solving the equation for a we have:
Therefore the acceleration of the system is 2.42 meters per second per second.
Part B.
Now, that we have the acceleration of the system we analyze the lower block individually; for this block the equation of motion is:
where T' is the tension in the lower rope, W' is the weight of the lower block and m2 is its mass. Solving for the tension we have that:
Therefore the tension in the lower rope is 2.93 N