Will mark a biker sets out from point a to point b. during the first hour he gets 0.25 of the way there; during the second hour he covers 0.2 of the distance and, during the third hour, he covers 0.3 of the distance. after three hours, what part of the total distance has the biker traveled, and what part of his trip does he still have to go?

Let 'x' represent the total distance from point A to point B

During the first hour he gets 0.25 of the way there: 0.25x

During the second hour he covers an additional 0.2 of the distance: 0.2x

During the third hour, he covers 0.3 of the distance: 0.3x

The total distance the biker traveled is:

0.25x + 0.2x + 0.3x = (0.25 + 0.2 + 0.3)x = 0.75x

The biker has: x - 0.75x = (1 - 0.75)x = 0.25x of the total distance left to go.