What are the voltages across different points in a circuit?

[M.Samad-CNAQ-]

Homework Statement

http://i52.tinypic.com/11loqy0.png

Find Va,Vb,Vab and current flowing from V1.(a,b,ab are subscripts.)

Homework Equations

hmm like
Vx=Rx/Rt x E

The Attempt at a Solution

i can find voltages across resistors but i dunt know how to find voltages across points.

 

[gneill]

Find the potential at each point with respect to some common reference point. Then find the difference between those potentials.