Find the speed limit

Question

A person drives 390 miles on a stretch of road. Half the distance is driven traveling 5
miles per hour below the speed limit, and half the distance is driven traveling 5 miles per
hour above the speed limit. If the time spent traveling at the slower speed exceeds the
time spent traveling at the faster speed by 24 minutes, find the speed limit.

Answer 1

For half of the trip: 195 miles = (L-5)(t+0.4) ... distance = rate in mi/hr multiplied by time, in hours.

Other half:             195         = (L+5)(t) where t is time of travel at faster speed.  Note: 24 minutes = 0.4 hour; L = speed limit.

 

That's the setup.  Can you solve now?  [System of two equations, with two unknowns]