Question 62529
Let the speed of the hiker be x mph
So speed of the bicyclist = 3x mph
Distance travelled by the hiker in 3 hrs = 3x miles.
Distance travelled by the bicyclist in 3 hrs = 3*3x
                                             = 9x miles.

Distance they are apart = 24 miles.

==> 9x - 3x = 24
==> 6x = 24
==> 6x/6 = 24/6
==> x = 4

==> the hiker travels at 4 mph.

Good Luck!!!