Medium Difficulty Math Problem

I haven't done real math in a couple of years in college.  An haven't done true algebra for almost a decade now, but I was just confronted with a real math problem I didn't know how to do.  I actually had to read off someone else's code to figure it out and see whats going on.  I suspect others have might have this same problem so I decided to brush up on my math skills a bit and expect almost every programmer to do the same.

The problem I had is this:

I know there is a name for this problem, but it escapes me at this moment.

I have k, a static number that never changes is multiplied by 50% to 150 percent on a random basis.  The answer will be k multiplied by 50% to 150% randomly and I have to figure out what 'k' is through the answers I get.

k * .50-1.50 = 15000
k * .50-1.50 = 12000

So if I have the equation above, I have to find where 15000/(.5 - 1.5) and 12000/(.5 - 1.5) intersect. The intersection point(s) could be k. I also get the chance to add as many (answers) to the equation as possible so I can define my answer more and more if I would like.

So here is the problem.  If I do have the numbers 15000 and 12000, what is k?

Good Luck and tell me in the comments how you did it and the actual answer(s).  I will post the answer(s) on Monday.

Have Fun!