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

----------------

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.