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David canoes 20km downstream in 2.5 hours his return trip takes 4 hours find the rate of his current. A 1.5 km/h B 1 km/h C 0.5 km/h D 2.5 km/h

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Answer:

1.5 km/hour

Step-by-step explanation:

d is the David's speed in still water

c is the speed of the current

Going with the current, he travels d+c km per hour.

Going against the current, he travels d-c km per hour.

d+c = (20 km)/(2.5 hours) = 8 km/hour

d-c = (20 km)/(4 hours) = 5 km/hour

Add the equations to eliminate the c terms

d+c = 8

d-c = 5

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2d = 13

d = 6.5 km/hour

c = 8-d = 1.5 km/hour