（1）10.5-4.28-5.72（2）14/9*11/10-5/9*11/10（3）（1/6+7/15）/2/5+5/12要脱式计算（能简算的要简算）

10.5-4.28-5.72
=10.5-(4.28+5.72)
=10.5-10
=0.5
14/9*11/10-5/9*11/10
=(14/9-5/9)*11/10
=1*11/10
=11/10
(1/6+7/15）/(2/5)+5/12
=(1/6+7/15)*5/2+5/12
=1/6*5/2+7/15*5/2+5/12
=5/12+7/6+5/12
=5/12+5/12+7/6
=5/6+7/6
=2