Word problem

Question

A motorboat travels 372 km in 6 hours going upstream and 936 km in 9 hours going downstream. what is the rate of the boat in still water and what is the rate of the current? 

Answer 1

distance=rate*time

372=(r-c)*6

936=(r+c)*9

simplify both equations

62=r-c

104=r+c

add

166=2r

r=166/2

r=83 kph is the rate of the boat

104=83+c

c=104-83

c=21 kph is the rate of the current