[davieddy]

Applying Newton's 2nd law to the top block we get
T - 9.8*1*0.37 = 1*a

For the bottom block we get
20 - T - 9.8*1*0.37 - 9.8*3*0.37 = 2*a

Adding the equations gives
20 - 9.8*5*0.37 = 3*a

David

Sorry to be too explicit for the homework help roolz :)