Porential across current source

[Altairs]

Homework Statement

Title says it all. Question is attached.

Homework Equations

Simple KCLs, KVLs etc

The Attempt at a Solution

What I don't get is that isn't I_{R_{4}} = \frac{R_{3}}{R_{3}+R_{4}} * I1

 

[CEL]

Homework Statement

Title says it all. Question is attached.

Homework Equations

Simple KCLs, KVLs etc

The Attempt at a Solution

What I don't get is that isn't I_{R_{4}} = \frac{R_{3}}{R_{3}+R_{4}} * I1

This expression is for a current divider. It would be valid if R3 and R4 were in parallel, which they are not.
Write Kirchoff's equations for the 3 loops to obtain the voltages on the terminals of R4 and R2. The voltage on the source is the difference between them.