Help with forces in equilibrium - simple problem

Diagram:
The body is represented by single dot in the centre. A force of 15N pushes it downwards, a force 'F' pushes it to the left, a force of 20N pushes it north easy at an angle of x to the horizontal

The object is in equilibrium, which equation is correct about the forces?
A. 15 = 20 cos x
B. 20 = F cos x
C. F = 15 sin x
D. F = 15 tan x

I keep getting answers which aren't part of the selection of choices so could anyone please explain how to do it so I would know where I went wrong?

Here's a link to the diagram if anyone is having trouble visualising it:
http://s1048.photobucket.com/albums/s365…

Thanks for the help!

You're Right. The answer's not there.
Since the forces must balance you have;
Vertcal; 15 = 20Sin()
Horiz. : F = 20Cos()

And if you divide those two eqs you can get;
15/F = Tan()
15 = FTan()

There are no other possibilities involving Sin, Cosine or Tan.