# Average friction force for an object going up a slope

What is the difference between frictional force and average force of friction?

I know we calculate frictional force in a typical slope problem by finding out the forces that act in opposition, most commonly $$F_f = mg\sin\theta$$ in most slope problems.

A problem is asking me to find average force of friction, and the method mentioned above is not working, so I assume that average force of friction is a whole different value. My peers have said it is calculated by using $$W = F*d$$ (given the values of $$W$$ and $$d$$) Why are these two different forces a different value? What is different about average force of friction?