Answer
option B)
19N
Explanation
If the object is at equilibrium, then the net force acting upon the object should be 0 N. Thus, if all the forces are added together, horizontal and vertical forces separately, then the resultant force (the vector sum) should be 0 Newton.
As we only need to find the magnitude of x-component of force F (which i assume is the 4th force which makes it equilibrium)
so find all x component/horizontal forces acting on the object.
50cos(40) - 40cos(25) + 30cos(55) + x = 0
38.30 - 36.25 + 17.21 + x + = 0
19.26 + x = 0
x = - 19.26
x ≈ 19 (magnitude only)
