Load Voltage Problem - Find the Fault!

[alexmath]

Homework Statement

Problem is in the pic. uploaded.

Homework Equations

The Attempt at a Solution

Also in the pic. The right answer is -3, where is the fault? Thank you!

 

[mfb]

It is hard to read your approach.
You just consider I2 to calculate the final voltage, but there is also I1 flowing through the resistor. And you should use units in a consistent way.

 

[alexmath]

You are right. My mistake!