Question 90438
[6/x-2] + [?/2-x] = [13/x-2]
Rearrange the 2nd term as follows:
[6/x-2] - [?/x-2] = [13/x-2] 
Now, multiply thru by (x-2) top get:
6 - ? = 13
? = -7
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Cheers,
Stan H.