Question 286389
Please answer the following story problem. The speed of a boar in still water is 20 mph. If the boar travels 140 miles downstream in the same time that it takes to travel 92 miles upstream, find the speed of the current. 
I have the rates s/b downstream 20+x and upstream 20-x But that is the extent right now.

Good Start!

Distance = rate*time so

Letting t be the common travel time for both trips.

We have for the upstream trip:

1.) 90 =  (20-x)*t

and for the downstream trip:

2.) 140 = (20+x)*t

Solving 1.) for t we have:

t = 90/(20-x)

Substituting 90/(20-x) for t in equation 2.) then we have:

140 = (20+x)*(90/(20-x))

To simplify, multiply both sides by (20-x):

140*(20-x)= (20+x)*90

Expand and solve the above for x.