Finding the voltage in a resistance

[znaya]

Homework Statement

Given the circuit in the image (with a current source of 2A and several resistors), what's the voltage in R3?

http://postimg.org/image/yl6czh9u7/

The answer options are:
1.1V
0.77V
50V
0.55V

Homework Equations

Ohm's law.
V=RI

The Attempt at a Solution

I tried to simplify the circuit. The circuit equivalent resistor I found was
(((((R6 || R7) + R5) || R8) + R4) || R3) + R1 + R2
From my calculation the equivalent resistor is 32,5Ω
And the voltage of the circuit is 65V
If the voltage in R1 is 10V (2A x 5Ω) and in R2 is 30V (2A x 15Ω) in R3 it should be something like 25V... but that is none of the options!
Thanks for any help.

 

[mfb]

I agree with your analysis and I got the same result.

Here is a nice shortcut once you have the expression for the equivalent resistor: you have R3 and an equivalent resistance of 25 Ohm in parallel, so the 2 A will be split in two equal parts - R3 will get 1 A and therefore a voltage of 25 V.

 

[znaya]

I tried to solve this problem hundreds of times using different approaches and the result was always 25Ω.
Maybe the professor mistook when he chose the answer options...