Question

can anyone explain me, how to do this :)

Answer 1

http://screencast.com/t/9rLKW4k9

Answer 2

@Callisto @ParthKohli @UnkleRhaukus @Hero

Answer 3

As you can see, the total horizontal force is
\[F_x=2F cos \theta \\ where\; cos \theta=\frac{3}{5}\]