SOLUTION: Hi, here's my question: Charlie rows at a constant speed downstream in the river from Amaroo to Bradden in 3 hours and back upstream in 4 hours. Assume the river flows at a cons

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Question 982494: Hi, here's my question:
Charlie rows at a constant speed downstream in the river from Amaroo to Bradden in 3 hours and back upstream in 4 hours. Assume the river flows at a constant rate. Let the river's flowing rate be xkm/hr and Charlie's rowing speed (km/hr) be y km/hr, express y in terms of x.
Please include an understandable explanation and thank you so so much! :)
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
Distance between two places stays the same:
D=distance
Rate downstream is rowing+current=y+x
Rate upstream is rowing-current=y-x
Distance=rate x time
.
Upstream:
D=(y-x)(4hrs)
Downstream:
D=(y+x)(3hrs)
.
Since D=D:
(y-x)(4hrs)=(y+x)(3hrs)
(4y)hrs-(4x)hrs=(3y)hrs+(3x)hrs
(y)hrs=(7x)hrs Divide each side by 1 hour.
y=7x