Question 198578
1/5 - 1/y
__________ 
5-y/5
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[(y-5)/(5y)] / [(25-y)/5]

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Invert the denominator and multiply to get:
= [(y-5)/(5y)] * [5/(25-y)]

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Cancel the "5" factor to get:

= (y-5)/(y(25-y))
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Cheers,
Stan H.