Please solve this word problem and explain how you solved it, thank you.

Question

 

Zoe and Linda could go 52 miles downstream in the same time it took them to go 28 miles upstream.  If the speed of their boat in still water was 10 mph, what was the speed of the current?

a.  4 mph                                               b.  3 mph

c.  80 mph                                             d.  20 mph 
 

 

Answer 1

distance =speed x time

distance downstream =10 +r

distrance upstream =10-r

52/ (10+r) =28/ (10-r)

52(10-r) =28(r+10)

520 -52r =28r +280

240 =80r

r=3 mph