Answer
See the figure below.
Work Step by Step
Since the object is in equilibrium, the net force exerted on it must be zero.
So that
$$F_x=0 \;\;\;\;{\rm and }\;\;\;\;F_y=0$$
It seems that the two forces are having the same magnitude, the same horizontal components, and the same vertical components.
It is also obvious that the vertical components are in opposite directions. This means that the third force had to have a negative horizontal force component and a zero vertical force component, as we see below.