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.
