First, put the terms with x on one side and the rest on the other side.Then, factor x out and divide both sides to have the x alone on one side.Finally,simplify.
Ok, take this example
https://www.physicsforums.com/showthread.php?t=376316
Two important things you should know
1-http://en.wikipedia.org/wiki/Ohm%27s_law"
2-http://en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws"
Using Ohm's and Kirchhoff's Current Laws, you will end up with...
If you transform the resistors you will lose the given information.To solve the problem,assign a current at every brunch and use KCL at every essential node.
Because of the current source you can't apply KVL at that loop, unless you know the voltage across the current source
However,this is simple circuit you can usehttp://en.wikipedia.org/wiki/Source_transformation"
As I said before use the mesh analysis
there are two meshes you will have two equations to solve
http://en.wikipedia.org/wiki/Mesh_analysis
or you can use Nodal analysis , which is better in this case
http://en.wikipedia.org/wiki/Nodal_analysis
Work done on or by a system
It depend on which reference your book choice
some books take the work done on a system as negative and in other books positive
Two loads are in parallel if their terminals connected to the same two nodes ( they have the same voltage across the terminals)
Hence, there are 3 nodes in this circuit
Keep in mind that in the logic diagram
you will implement it in two-level NAND gate
for example if you have this function f(w,x,y )=xy+xz+w
In the first level you will have (xy)' , (xz)' , w'
Then the second level [(xy)'(xz)'w']'=xy+xz+w