15.58÷8.2-0.72
=0.9-0.72
=0.18
4.5×1.2-3.15÷15
=5.4-0.21
=5.19不是硬算，是简便运算~~~~上面打错了...是1.9-0.72=1.18这...学太久，可能忘了吧 - -你看看这样对不对15.58÷8.2-0.72=15.58÷8.2+0.1-0.1-0.72=(15.58+0.82)÷8.2-0.1-0.72=16.4÷8.2-0.1-0.72=2-0.82=1.184.5×1.2-3.15÷15=4.5×2×0.6-3.15×10÷15÷10=9×0.6-31.5÷15÷10=5.4-2.1÷10=5.4-0.21=5.19