Make sure to draw a free body diagram with an arrow to the right of 94.4 N, left 128.6 N, up with 509 N and down with 246.8 N. Assuming a traditional coordinate system with x direction left/right and y direction up/down, you only need to worry about the left/right forces since the question is asking about the forces in the x-direction.
The net external force will be the forces summed in the x-direction. Once again, assuming a traditional coordinate system, define +x to the right and -x to the left. Thus, the sum of the forces in the x direction is:
Sum Fx = 94.4 N - 128.6 N = -34.2 N
So the net external force in the x direction is -34.2 N, or the net force will be pushing it to the left (defined as negative x direction).
