Respuesta :
Answer:
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=12miles;rate=15+c mph; time=d/r =12/(15+c)hrs.
Upstream info;
distance=9miles;rate=15-c mph;time=d/r=9/(15-c)hrs.
I hope it's helpful!
