Question 172780
I am guessing that there must be some missing info (like maybe investing for more than a single year).

It "doesn't work" because given the numbers you have - "you can't get there from here".

Let's say the broker put the entire amount at 8% for a year. In that case, the interest is 13000*08 = 1040. Which is less than the value the problem stated was returned.

The math does not lie. The reason 46000>13000 is because the math, as provided, doesn't "work".

When you get an answer that doesn't make sense, like 5 = 7 or somesuch, then that means "you can't do whatever was being suggested could be done".

The fact that you were aware enough to realize that the answer is not 46000 and -33000 shows you are on the right track mathematically. Good for you!