2)6 7/9 - 3 22 /27 = 61/9 - 103/27=(183-103)/27=80/27=2 26/27;
4)8 13/20 - 5 27/40=173/20 - 227/40=(346-227)/40=119/40= 2 39/40;
6)15 4/9-9 17/18=139/9 - 179/18=(278 - 179)/18=5 1/2= 5,5;
8)43 21/26 - 28 11/13=1139/26 - 375/13=(1139-750)/26=389/26=14 25/26.