Choice A is one of the answers. Nice work. This is because x+x+x turns into 3x.
Choice D is the other answer because 2(x+1) + x = 2x+2+x = 3x+2. You can find this through trial and error. Or you could graph y = x+x+x+2 and y = 2(x+1)+2 to find that they are the same exact identical diagonal line. A non-graph approach would be to set up a table of values to see that the two tables are identical.
Since the forces exerted on the box are equal and opposite in direction, the net force will be 0, so the box will not move.
A way to think of this is the equal forces in opposite directions cancel each other out, so the net force is 0.
One fraction is 2/5.
another one is 12/30.
HOPE I HELPED!!!