Posted by alicia on Monday, February 7, 2011 at 4:38am.
need help.
Young salmon hatch in freshwater steams and then migrate downstream to the ocean at the rate of 70 miles in 8 hours. there they live until they reach spawning age. then they return upstream to fresh water to spawn and usually die soon after. on the upstream trip, the salmon travel about 58 miles in 8 hours. find the rate of the salmon swimming in still water and the rate of the current.
this is what I have so far, but it doesnt add up
r*t=d
downstream= 8(x+y)=70
upstream=8(xy)=58

math  drwls, Monday, February 7, 2011 at 5:46am
OK, it looks like you have chosen x for the rate in still water and y for the speed of the current. The equations you should have written are:
x + y = 70/8
x  y = 58/8
which is the same as you have written.
Adding them gives
2x = 128/8 = 16
x = 6 mph
y = 70/8  6 = 2.75 mph
You started the problem correctly and only needed to finish.
Answer This Question
Related Questions
 Math  A salmon swims 15 miles downstream from its birth to the ocean in 3 hours...
 math  a boat travels 10 miles upstream in 4 hours. the boat travels the same ...
 word problem  A motor boat took 4 hours to make a downstream trip with a ...
 math  A salmon has to swim 25 miles upstream. It seems 7 miles each day and ...
 Algerbra  A boat's crew rowed 10.5 miles downstream, with the current, in 1.5 ...
 algebra  A boat's crew rowed 13.5 miles downstream, with the current, in 1.5 ...
 math  A salmon has to swim 25 miles upstream. It swims 7 miles each day and ...
 Algebra  The current of a river moves at 3 miles per hour. It takes a boat 3 ...
 math  A boat's crew rowed 12 miles downstream, with the current, in 1.5 hours. ...
 algebra  36 Upstream, downstream. Juniorâ€™s boat will go 15 miles per hour in ...
More Related Questions