Word problem help

Question

On a particular day, the wind added 4 miles per hour to Jaime's rate when she was rowing with the wind and subtracted 4 miles per hour from her rate on her return trip.  Jaime found that in the same amount of time she could row 63 miles with the wind, she could go only 39 miles against the wind.  What is her normal owing speed with no wind?

Answer 1

Use the distance formula to solve this problem:  d = vt

 

Let's say s is the rate or speed.

 

With wind:  s + 4

Against wind:  s - 4

 

63 = (s + 4)t

39 = (s-4)t

 

Set the two equations equal to each other:

(s + 4)t / 63 = (s - 4)t / 39

 

Divide both sides by (s + 4)(s - 4) to get the following:

 

63(s - 4) = 39(s + 4)

63s - 252 = 39s + 156

24s = 408

s = 17 mph (normal rowing speed with no wind)