Find speed limit and equation

Question

A person drives 390 Miles on a stretch of road. Half the distance is driven traveling 5 mph below the speed limit, and half the distance is driven 5 mph 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

195/(r-5) = 195/(r+5) + 24/60 (Remember the car speed is in mph; you need to convert the 24 minutes to hours).

Clear fractions: 195(r+5) = 195(r-5) + (2/5)(r² -25)

1950 = (2/5)(r² - 25)

1960 = (2/5)r²

You take it from here.