tension, vectors and angles, oh my

hi, i'm having trouble with another question:

2. A block of weight W is attached to the ceiling by a cord which makes an angle
θ = 30° to the vertical, and to the wall by a horizontal cord. If the tension in the cord
attached to the ceiling is 20 N, the tension in the horizontal cord will be
A) 20 N
B) 17 N
C) 12 N
D) 10 N

I keep getting to wrong answer. I'm really bad with angles and stuff, so I'm not sure how to solve this. Any help would be appreciated.
 Mentor Blog Entries: 1 Since the block is in equilibrium, you should know that the vertical and horizontal components of the forces on it must add to zero. Hint: Consider the horizontal components.
 This is a typical "Statics" question - there should be a lot of examples in your textbook.

tension, vectors and angles, oh my

my textbook is a conceptual physics textbook....only theory is covered...so there are no examples......
 Recognitions: Homework Help Make a sketch with the two ropes. Split the tension in the rope into horizontal and vertical components. The vertical component will be supporting the weight of the block. The horizontal component will be resisting the pull of the other, horizontal rope. Clear?