1、0.72/(0.3*0.2+0.18)
=0.72/[0.3(0.2+0.6)]
=(0.72/0.3)(0.72/0.8)
=2.4*0.9
=3.16
2、7.75[20/(3.24-3.04)]
=7.75/(20/0.2)
=7.75/100
=0.0775
1、0.72÷(0.3×0.2+0.18)
=0.72÷(0.3×0.2)+0.72÷0.18
=12+4
=16
2、7.75×(20÷(3.24-3.04))
=7.75×(20÷0.2)
=7.75 ×100
=775