Ok plz answer and tell me how to do it

25N

method: total force in the right hand direction is 100N and total force in the left hand direction is 125N. To get the net force, we add forces if they are in the same direction and substract if they are in opposite directions. since 100N and 125N are in opposite directions, we substract the larger value from the smaller value. Then we get 25N in the left hand direction as the final answer.

Pe = 1/2k(x)^2  and .05n/m = .05x10^-9m = x