Trying to get equivalent resistance of a circuit

[AmirWG]

i had a problem in my textbook asking me to get equivalent resistance of a circuit , i ended up getting 23.7 ohm as my answer but my textbook says that the correct answer is 100 ohm
you can see my attempt here :
imgur link :


i really want to know what went wrong with my steps
thanks in advance

 

[tnich]

When you are analyzing a circuit, it helps to redraw it so that it is really clear what components are in parallel, and what are in series. In this case, you could redraw it to look like this:

I suggest that you fill in the dashed portions of this diagram with the appropriate resistances and then do your series/parallel calculations.

 

[AmirWG]

When you are analyzing a circuit, it helps to redraw it so that it is really clear what components are in parallel, and what are in series. In this case, you could redraw it to look like this:
View attachment 248018
I suggest that you fill in the dashed portions of this diagram with the appropriate resistances and then do your series/parallel calculations.

i can now see why my steps went wrong and i am even able to get the correct answer now , thanks a lot for helping (:

 

[FactChecker]

One way to see immediately that the answer must be at least 85 is to notice that there is no way around the 50 and 35-ohm resisters. So there is a resistance of 85 to start with.