45×(100-8)=45×100-45×8=4500-360=4140
原式=45(100-10+2)=4500-450+90=4000+500-450+90=4000+50+90=4000+140=4140
45(100-8) =45×100-45×8 =4500-350 =4140
45×(100-8)=45x100-45x(2x4)=4500-45x2x4=4500-90x4=4500-360=4140