I notice that your problem is similar to the circuit worked on the page:

Examples
In terms of the variables in that problem

$\displaystyle V_a = 10 $

$\displaystyle V_b = 14 $

to allow for the effect of the 2 volt battery.

You would have to solve the simultaneous eq 4 & 5 on that page without assuming all resistors are the same. (I dont know why that page introduced that assumption.)