SOLUTION: Karen traveled 640 miles by boat and returned by plane. She spent 42 hours traveling on the trip. If the rate of the plane is 20 times faster than the rate of the boat, find each

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Question 632285: Karen traveled 640 miles by boat and returned by plane. She spent 42 hours traveling on the trip. If the rate of the plane is 20 times faster than the rate of the boat, find each rate.
Answer by mananth(16949) About Me  (Show Source):
You can put this solution on YOUR website!
let boat speed = x mph
plane speed = 20 x

Time forward + time return = 42 hours
distance one way = 640 miles
time = d/r
640/x + 640/20x= 42
LCD = 20x
(640*20 +640)/20x= 42
12800 +640= 42*20x
13440= 840x
x= 13440/840
x= 16 mph the speed of boat
speed of plane = 16*20 = 320 mph
m.ananth@hotmail.ca