Solve the problem

Question

Julie and Eric row their boat(at a constant speed) 24 miles downstream for 4 hours, helped by the current. Rowing at the same rate, the trip back against the current takes 6 hours. Find the rate of the current. 

( solve by involving motion)

 

 

 

 

 

 

 

(p.s. the answer is: 1 mph but i need help in how they got this answer)

 

 

 

 

 

 

 

 

 

 

Answer 1

distance=rate*time

24=(r+c)4 where r=rate of the boat and c=rate of the current

24=(r-c)6 (this is upstream and the above is downstream)

simplify both equations

6=(r+c)

4=(r-c)

add the equations

10=2r

r=10/2

r=5 mph for the rate of the boat

6=5+c and 6-5=c, c=1 mph for the current, or

4=5-c and 4-5=-c, -1=-c, c=1 mph again for the current