2+1/4×8
=2+2
=4
12×(2/3-1/4)
=12×2/3-12×1/4
=8-3
=5
5/9×4/7×7/10
=5/9×(4/7×7/10)
=5/9×2/5
=2/9
5/8*7/10-7/10*5/8
=5/8*(7/10-7/10)
=5/8*0
=0
15/16*15
=(1-1/16)*15
=15-15/16
=14又1/16
53/54*55
=53/54*(54+1)
=53+53/54
=53又53/54
2+1/4×8
=2+2
=4
12×(2/3-1/4)
=12×2/3-12×1/4
=8-3
=5
5/9×4/7×7/10
=5/9×(4/7×7/10)
=5/9×2/5
=2/9
5/8*7/10-7/10*5/8
=5/8*(7/10-7/10)
=5/8*0
=0
15/16*15
=(1-1/16)*15
=15-15/16
=14又1/16
53/54*55
=53/54*(54+1)
=53+53/54
=53又53/54