Answer to July 2002 Newsletter Brain Teaser:

Milepost 900

To solve this problem, recall that rate x time = distance.
--Let Z be the time it takes the Grand Central Steamer to reach the milepost.
--Then 60 mph x (Z + 3) = 75 mph x Z.
--60Z + 180 = 75Z
--15Z = 180
--Z = 12 hours
--75 x 12 = 900 miles