d = r · t and we know that the distance is the same.
Let x = time it takes Evelyn (in hours, since the rate is mph).
Evelyn's distance is 84x.
Rick's distance is 36·(x+2/3) since 40 minutes longer is 2/3 of an hour longer
84x = 36(x+2/3)
84x = 36x + 24
48x = 24
x = 1/2
So it takes Evelyn 1/2 an hour, meaning the distance is 84(1/2) = 42 miles
To confirm this, it would take Rick 42/36 hours or 1 and 1/6 hours. That's 70 minutes, which is 40 minutes longer than Evelyn's 1/2 hour trip.
The distance is 42 miles.
