Question

A boat in still water is 32 mph. If the boat travels 72 miles upstream in the same time that it takes to travel 120 miles downstream, find the speed of the current.

Answer 1

dup= 72 miles 
ddown= 120 miles 
v= riverspeed 
rup= 32mph - v 
rdown= 32mph + v 
t both ways= t 

d=r*t 
d/r=t 

t=ddown/rdown 
t=dup/rup 

dup/rup = ddown/rdown 

(72)/(32-v)=(120)/(32+v) 
3840-120v=2304+72v 
1536=192v 
v=8