Question 1046929
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Two motorboats leave the dock at the same time and travel in opposite directions. One travels 9 mph faster than the other. 
After 2 hours the boats are 170 miles apart. How fast is each boat traveling?
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Let "x" be the rate (the speed) of the slower motorboat, in miles-per-hour.

Then the rate of the faster motorboat is (x+9) mph.

Then your equation is

2x + 2(x+9) = 170.

First addend in the left is the distance traveled by the slower motorboat in 2 hours.
Second addend in the left is the distance traveled by the faster motorboat in 2 hours.

Simplify and solve the equation for x:

4x + 18 = 170,

4x = 170 - 18,

4x = 152,

x = {{{152/4}}} = 38.

<U>Answer</U>. The speed of the slower motorboat is 38 mph. The speed of the faster motorboat is 38+9 = 47 mph.
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