I hate assignments like this. Okay, it's not *quite* that bad. But it's close. What I have to work with is a statement that's so similar to the "proof" that - to me - they're *the same thing*.
So I'm not quite sure what the teacher wants me to write. Should I just write the statement, then write the answer? Should I explicitly write out the single step that has to be done (namely, divide the equation by Ix)? I just know, whatever I do, I'll get points taken off.
Oh well. At least the next question is more interesting.