6 3/4 - 2 5/6 - 1 3/8 = 3 + 18/24 - 20/24 - 9/24=3 - 11/24 = 2 24/24 - 11/24 =
=2 13/24 .
9 8/15 - 4 1/12 + 3 7 /20 = 8 + 32/60 - 5/60 + 21/60 = 8 58/60 = 8 29/30.
7 5/8 + 3 2/3 -8 3/16 = 2 + 30/48 + 32/48 - 9/48 = 2 +53/48 = 3 5/48.
9 23/25 - 4 7/10 - 2 3/4 = 3+ 92/100 - 70/100 - 75/100= 3 - 53/100= 2 100/100 -
-53 /100 = 2 47/100.
20 -( 5 + 2/12 + 9/12) - 20 - 5 11/12 = 19 12/12 - 5 11/12 = 14 1/12.