posted by laura .
A box with a force of 100N is pushed up an inclined plane. It takes a force os 75N to push it to the top. What is the efficiency of the inclined plane?
I cannot determine what you mean by "a box with a force of 100N".
If you mean weight of 100N, the question has no answer, as the weight and the pushing force are in different directions.
The measure of "efficiency" is a measure of work: Work pushing is 75*distance up plane, the work done is 100*height raised (if 100N is the weight).
Mechanical advantage (note: this is NOT efficiency) is 100/75