
Nathan B. answered 04/21/17
Tutor
5
(20)
Elementary and Algebraic skilled
a = still water movement and b = current's effect on movement
Let's start by using the elimination method:
a + b = 186 miles in x hours
a - b = 102 miles in x hours
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2a = 288 miles in x hours
a = 144 miles in x hours
In other words, if the water is still, the boat travels 144 miles in the given time x.
Now to find the current's effect (b):
144 + b = 186
b = 42
check:
144 - 42 = 102
102 = 102
Now take the still water travel distance and divide by its speed to find out how long it traveled:
144 miles / 24 mph = 6 hours traveled
So the given time is 6 hours.
42 miles affected by the current ÷ 6 hours = 7 mph for the current.