<PRE><B>Question 54818</B>
Resolution:
3   4   5   6       18
- x - x - x - x...x -  = 9
2   3   4   5       17

since this is a multiplication of fractions, you can cancel 3 on top and bottom, the same 4, 5 , 6, 7......17. 

after canceling you the product end as follow:

18 = 9 where a = 18 and b = 2; the sum of a + b = 20.
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