Răspuns:
a.
8/15-4/15-1/15=(3/15)⁽³=1/5
8/15-(4/15+1/15)=8/15-6/15=2/15
8/15-4/15-1/15 ≠ 8/15-(4/15+1/15)
b.
13/14-(5/14-3/14)=13/14-2/14=11/14
13/14-5/14+3/14=11/14
13/14-(5/14-3/14) = 13/14-5/14+3/14
c.
(4×9+5)/9-(2×9+1)/9=41/9-19/9=22/9
⁹⁾2+4/9=22/9
(4×9+5)/9-(2×9+1)/9=⁹⁾2+4/9=(2×9+4)/9
