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`1) 5/6 - 8/9`

`MC = BCN N(6,9) = 18`

`5/6 = (5.3)/(6.3) = 15/18 ; 8/9 = (8.2)/(9.2) = -1/18`

`=> 15/18 - 16/18 = -1/18`

 `2) 5/6 - 5/4`

`MC = BCN N(6,4) = 12`

`5/6 = (2.5)/(6.2) = 10/12 ; 5/4 = (5.3)/(4.3) = 15/12`

`=> 10/12 - 15/12 = -5/12`

`5) -3/8 - 5/12`

`MC = BCN N(8,12) = 24`

`-3/8 = (-3.3)/(8.3) = -9/24 ; -5/12 = (-5.2)/(12.2) = -10/24`

`=> -9/24-10/24 = -19/24`

`6) -4/9 - (-5/6)`

`= -4/9 + 5/6`

`MC = BCN N(9,6) = 18`

`-4/9 = (-4.2)/(9.2) = -8/18 ; 5/6 = (5.3)/(6.3) = 15/18`

`=> -8/18 + 15/18 = 7/18`

`9) -1/12 - 4/15`

`MC = BCN N(12,15) = 60`

`-1/12 = (-1.5)/(12.5) = -5/60 ; -4/15 = (-4.4)/(15.4) = -16/60`

`=> -5/60 - 16/60 = -21/60 = -7/20`

`10) -1/15 - 3/10`

`MC = BCN N(15,30) = 30`

`-1/15 = (-1.2)/(15.2) = -2/30 ;  -3/10 = (-3.3)/(10.3) = -9/30`

`=> -2/30 - 9/30 = -11/30`

`13) 7/-10 - 3/25`

`= -7/10 - 3/25`

`MC = BCN N(10,25) = 50`

`-7/10 = (-7.5)/(10.5) = -35/50 ; -3/25 = (-3.2)/(25.2) = -6/50`

`=> -35/50 - 6/50 =  -41/50`

`14) -1/12 - 5/16`

`MC = BCN N(12,16)= 48`

`-1/12 = (-1.4)/(12.4) = -4/48 , -5/16 = (-5.3)/(16.3) = -15/48`

`=> -4/48 - 15/48 = -19/48`