Question 1117514
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Let *[tex \Large x] represent the number of hours Art would take to build the bridge.  Then *[tex \Large x\,+\,15] is the number of hours that Paul would take by himself.


That means that Art could build *[tex \Large \frac{1}{x}] of the bridge by himself in one hour.  Likewise Paul could build *[tex \Large \frac{1}{x\,+\,15}] of the bridge in one hour.  Adding these two amounts is the fraction of the bridge that the two working together could build in one hour, namely, *[tex \Large \frac{1}{4}].  Hence:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{1}{x}\ +\ \frac{1}{x\,+\,15}\ =\ \frac{1}{4}]


Solve for *[tex \Large x].  Hint:  The equation reduces to a quadratic for which there are two solutions.  The fact that no one, including Art, can build something in a negative number of hours should guide you to choose the correct solution.


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it
<img src="http://c0rk.blogs.com/gr0undzer0/darwin-fish.jpg">
*[tex \Large \ \
*[tex \LARGE \ \ \ \ \ \ \ \ \ \  

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