Two pulleys system (please check my work)

[fishingspree2]

Homework Statement

Find the acceleration of the system
http://img266.imageshack.us/img266/4904/2pulleyszw9.jpg
The rope is massless
The mobile pulley is not massless, it weighs 20 grams.
Find the accelereation of the system

Homework Equations

F=mg
F=ma
g = 9.8

The Attempt at a Solution

for W1:
Fy = 2T-W1 = ma
2T-(500+20)*g = (500+20)*a
2T-520g = 520a (equation 1)

for W2:
Fy = W2-T=ma
300g-T=300a
T = 300(g-a) (equation 2)

equation 2 in equation 1 gives
a = 1,43


Is it correct?

 

[fishingspree2]

i don't think it's correct.. i think there is an error in the tensions, but i don't see

 

[fishingspree2]

can someone help me?
I really want to know how to do this =(

 

[nasu]

The equations seem to be OK. The solution is not. Try to solve again the two equations.
If you show how you solve them I can try to find the mistake, if any.
Be careful with the units. If you want to get the tension in Newtons, the mass should be in kg.