----
After sailing 14 mi, a sailor changed direction and increased the boat's speed by 4 mph. An additional 15 mi was sailed at the increased speed. The total sailing time was 3 h. Find the rate of the boat for the first 14 mi.
----
SPEED TIME DISTANCE
First Part r 14/r 14
Second Part r+4 15/(r+4) 15
Total 3