Question 375606
let speed of current be x mph
speed of boat in still water = 15 mph
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downstream speed = x+15
upstream speed = 15-x
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downstream distance = 12 miles
upstream distance = 9 miles.
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t= d/r
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upstream time = downstream time
12/(x+15)= 9/(15-x)
12(15-x)=9(x+15)
180-12x=9x+135
21x=180-135
21x=45
/21
x= 45/21
x= 2.14 mph speed of current
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m.ananth@hotmail.ca