Question 449602
The question is the rate that a boat travels in still water is r and the current speed is c miles per hour.
 It takes 1.5 hours to travel 4 miles downstream." Do I add or subtract c and r

Downstream, you add r and c: (r+c)
Upstream, you subtract c from r; (r-c)
:
The equation for,"It takes 1.5 hours to travel 4 miles downstream."
1.5(r + c) = 4