A boat takes 2 hours to travel 15 miles upriver against the current. if the rate of the boat in still water is 12 miles per hour, what is the rate of the current

2.1429 or 2 and 1/7

Step-by-step explanation:

Time = time

12 / (15+c) = 9 / (15-c)

12 (15-c) = 9 (15+c)

12*15 - 12c = 9*15 + 9c

21c = 3*15

c = 3*15/21

c = 45/21 = 2.1429 ... (speed of the current)

Downstream Info;

distance = 12 miles; rate = 15+c mph; time = d/r = 12 / (15+c) hrs.

Upstream Info:

distance = 9 miles; rate = 15-c mph; time = d/r = 9 / (15-c) hrs.