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Adding Fractions with Variables


Date: 03/21/97 at 11:00:27
From: lilly somer
Subject: Adding Fractions with Variables

What do I do here?

7/53 + 23/n = ?


Date: 03/21/97 at 11:25:32
From: Doctor Rob
Subject: Re: Adding Fractions with Variables

To add fractions, you need to find a common denominator.  This is a
number which is a multiple of both 53 and n.  In this case, 53*n
works.

Next you need to write each fraction using the common denominator
instead of its given one.  In this case, 7/53 = (7*n)/(53*n), 
by multiplying both numerator and denominator by n, and 
23/n = (53*23)/(53*n), by multiplying both numerator and 
denominator by 53.

Now that the fractions have the same denominator, you can add them
by adding the numerators and putting that sum over the common
denominator.  Then simplify the resulting fraction as much as
possible.

This is just the same process you learned when studying fractions
earlier, like adding 3/4 + 1/6.

-Doctor Rob,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Algebra

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