A jogger ran 4 miles, decreased her speed by 1 mile per hour, and then ran another 5 miles. If her total jogging time was 2 1/20 hours, find her speed for each part of her run.

Let the speed of the joker initially be x mi/hr

after reduction, the new speed will be: (x-1) mi/hr

but

time = (distance) / (speed)

hence:

Total time taken will be:

4/x+5 / (x+1) = 41/20

solving for x we get:

x=21.585 mi/hr

thus the initial speed was 21.585 mi/hr after reduction the new speed was 20.585 mi/hr