Answer:
The speed of the runner is 6 miles per hour.
Step-by-step explanation:
Given the distance between the cyclist and the runner is 68 miles.
Given the speed of the cyclist is 28 miles per hour.
Initial time is 1:00PM Final time is 3:00PM
Time elapsed is 3-1=2hours
Let the cyclist travel a distance of x miles,Then the distance travelled by the runner is 68-x miles.

for the cyclist

x=56 miles
the distance travelled by the runner is 68-56=12 miles
speed of the runner = 12/2 = 6 miles per hour