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  4  7/9   =   4 14/18
- 2 11/18  = - 2 11/18
—————————    —————————
               2  3/18 = 2 1/6
Explanation:
  4  7/9   
- 2 11/18
—————————   
           
The denominators are not the same, but I can make the
top one have a denominator of 18 by multiplying the 9 
denominator by 2.  But if I do that I have to multiply
the numerator by 2 also.  So I change the 7/9 to 14/18
  4  7/9   =   4 14/18
- 2 11/18 
—————————    
              
Then I just copy the rest over:
  4  7/9   =   4 14/18
- 2 11/18  = - 2 11/18
—————————    —————————
               
Now when I subtract I get
  4  7/9   =   4 14/18
- 2 11/18  = - 2 11/18
—————————    —————————
               2  3/18 = 2 1/6
Edwin
AnlytcPhil@aol.com