Let the distance of the race be d miles. We can now write the equation:
\(\frac{d}{7}+\frac{d}{3}=2\)
which when solved, gives the value of as 4.2 miles.
The time to walk 4.2 miles at 3 mph is 4.2/3 = 1.4 hours.
The answer is 1.4 hours or 1 hour 24 minutes.