Electric circuits plz help

https://www.dropbox.com/s/e2h09ux9n0gwd8c/20130928_005259-1.jpg

i tried to answer it but i am not sure if i got the correct
could anyone solve it and correct me if i did it wrong
plz i have exams :)

a ) R(equ) = 75.68
b) R(equ) =60.42
c) R(equ) = 3.58

1. 12//24=8,30//60=20,20 8 12=40//120=70 ohms


2. 9//18=6,75//50=3030 20=50//75=30,30 10=40,40//60=24 6=30//30=15 15=30 ohms

3. 54//27=18, 18 12=30, 80//20=16 14=30, 30//30=15, 2 3 15=20 ohms

use excel>>80//20>> =(80*20)/(80 20) put this into a cell and you get 16.
hope you can follow it.

a) has 12 and 24 in parallel, in series with 60 and 30 in parallel, in series with 12.
That is all in parallel with 120.
Finally, there are 2 series resistors, the 15 and 25. Add those to the result from above.
The other 2 are more complex, but if you break them down to what is in series and what is in parallel, you will slowly get there.
It is better you do these yourself, as to describe like above will be extremely hard for you to follow anyway.
I'll just describe the equivalency of the top 5 resistances of (b) as an example.
There is 35 + 40 in series, paralleled with 50. In series with this is 20, then all this is in parallel with 75.
That's the majority done. Go!

Take this stuff one pair of resistors at a time. It will be helpful to re-draw the circuit at each step.
For part a),

Req = {(60//30)+(12//24)+12}//120+15+25
= { 20 + 8 +12}//120+15+25
= 40//120 +15+25
= 30 +15+25
= 70