а) (7/15+2/9)-2/15 =5/9
7/15-2/15=5/15=1/3
1/3+2/9=3/9+2/9=5/9
б) 14/27-(5/27+1/6)=14/27-5/27-1/6=1/6
14/27-5/27=9/27=1/3
1/3-1/6=2/6-1/6=1/6
а) (7/15+2/9)-2/15 =5/9
7/15-2/15=5/15=1/3
1/3+2/9=3/9+2/9=5/9
б) 14/27-(5/27+1/6)=14/27-5/27-1/6=1/6
14/27-5/27=9/27=1/3
1/3-1/6=2/6-1/6=1/6