After sailing 18 mi, a sailor changed direction and increased the boat's speed by 2 mph. An additional 11 mi was sailed at the increased speed. The total sailing time was 3 h. Find the rate of the boat for the first 18 mi. mph

Look at the figure below: triangle abc is a right triangle with angle abc equal to 90 degrees. the length of ac is 5 units and the length of ab is 4 units. d is a point above c. triangle adc is a right triangle with angle dac equal to 90 degrees and dc parallel to ab. what is the length, in units, of segment cd?