in part A ..are we need to use law Y to dalta..??

and in part B ..how we found 4k and 12k..can we used parallel...?

 

in part A ..are we need to use law Y to dalta..??

and in part B ..how we found 4k and 12k..can we used parallel...?

It is kind of misleading how they are drawn. I slid the resistors a bit to make them look more like parallel and series that you can clearly group. All connections and values should be the same.

Reply if you need more hints. I'm going to bed but someone else can pitch in.