Question

David is rowing a boat upstream. The river is flowing at a speed of 2 miles per hour. David starts rowing at a speed of 6 miles per hour, and his speed decreases at a rate of 1.5 miles per hour.
The equation gives the speed of the boat after David has rowed for x hours.

Answer 1

Speed of boat = rowing speed - speed of current

rowing speed is a decreasing linear function, initially 6 and decreasing by 1.5 every hour.
---> 6 - 1.5x

Speed of boat = (6-1.5x) - 2 = 4 - 1.5x