The time, t, required to drive a certain distance varies inversely with the speed r. if it takes 12 hours to drive the distance at 60 miles per hour, how long ill it take to drive the same distance at 60 miles per hour, how long will it take to drive the same distance at 85 miles per hour.

If t varies inversely with r, then the equation looks like this: .  If t is 12 and r is 60, we need to use these to solve for k.  .  Solve for k to find that k = 720.  We will use that k value then to solve for a new t when r = 85.  .  This means it takes about 8.5 hours to drive a fixed distance going 85 mph, and it takes 12 hours to drive the same distance going 60 mph.  That makes sense because it takes longer to drive a distance if you're going slower.