15/12+2/15= 2целых 7/21+1целая 9/14= 17/30+5целых 7/45=
2/15 + 15/12 = 1 целая 23/60 2 целых 7/21 + 1 целая 9/14 = 3 целых 41/42 17/30 + 5 целых 7/45 = 5 целых 65/90
15/12+2/15=75/60+8/60=83/60=1ц.23/60 2ц.7/21+1ц.9/14=2ц.+1ц.+ 14/42+27/42=3ц.41/42 17/30+5ц.7/45=5 ц.+51/90+14/90=5ц.65/90 ____________________________________________