Answer:
8 miles per hour
Step-by-step explanation:
Let s represent Sue's running speed in miles per hour. Then her total exercise time was ...
time = distance/speed
4 = (16/s) + (1/(s/16)) . . . . . using distance in miles and time in hours
4 = 16/s +16/s = 32/s . . . . simplify
s = 32/4 = 8 . . . . . . . . . . . multiply by s/4
Sue's running speed was 8 miles per hour.