Answer:
Speed of river's current = 5 mph
Step-by-step explanation:
Let 'd' be the distance covered
Let x be the speed of the rivers current
Speed upstream = 15-x
speed downstream = 15+x
Time = distance / speed
time upstream = 
time downstream = 
the ferry trip upstream takes twice as long as its return trip downstream
= 
divide both sides by d
= 
cross multiply


Add 2x on both sideds

subtract 15 from both sides and divide by 3

x=5
Speed of river's current = 5 mph
Hope this helps you, and good luck in the future :)
Answer:
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Answer:
ONE-THIRD OF A GALLON DIVIDED BY 3 GALLONS EQUALS ONE-NINTH
Step-by-step explanation:=1/9
The answer is -7.137x10^-3