Matter. I don't really know how to explain it. Sorry. But anyways, Hope this helps!
The work done to pull the sled up to the hill is given by

where
F is the intensity of the force
d is the distance where the force is applied.
In our problem, the work done is

and the distance through which the force is applied is

, so we can calculate the average force by re-arranging the previous equation and by using these data:
If it increased its speed steadily at a constant rate, then the average speed for the minute was
(1/2)(10m/s + 20m/s) = 15 m/s .
Rolling at an average speed of 15 m/s for 1 minute (60 seconds), it travels
(15 m/s) (60 sec) = 900 meters