。①62.8×19+8×62.8-62.8=62.8(19+8-1)=62.8*26=1632.8 ②（1-1%×70）÷2/7=(1-7/10)*7/2=7/2-49/20=21/20
1=62.8x(19+8-1)=62.8x26=1632.82=(1-0.7)x7/2=2.1/2=1.05
1, =62.8x(19+8-1) 2.=.1x7/2-70/100x7/2=62.8x26
