To find slope, use the equation (y2-y1)/(x2-x1). In your case, the equation is going to look like (-3 - -1)/(5 - -2) or (-3 +1)/(5 + 2), and that simplifies to -2/7.
Step-by-step explanation:
Given that,
A motor boat travels 60 miles down a river in 3 hours but takes 5 hours to return upstream,
We know that,
Speed = distance/time
The rate while moving downstream
The rate while moving upstream 
The rate of the boat in still water is the average of these:

The rate of the current is the difference between the boat speed and actual speed = 16 mph - 12 mph = 4 mph
Hence, this is the required solution.
Im going to take a guess and say zero because any number times zero is zero.