Answer:
Yes that's right. Not really sure what your looking for as far as a reason goes. You performed the correct operations and got the right answer.
Both positive work and negative work have meaning: Positive work follows when the force has a component parallel to the displacement. Positive work adds energy to a system. Negative work follows when the force has a component opposite or against the displacement.
I am not sure if this is what your looking for but most machines use oil
445/100 - 5/4 = 445/100 - 125/100 = 320/100 = 16/5 = 3 1/5.
