数学思考题(简算,别用方程)x=乘

3.6x42.3x3.75-12.5x0.423x28
＝3.6x42.3x3.75-1.25x42.3x2.8
＝（3.6x3.75－1.25x2.8）x42.3
＝[（10.8-2.8）x1.25]x42.3
＝10x42.3
＝423
19.58x66+22x91.26
＝19.58x22x3+22x91.26
＝（58.74+91.26）x22
＝150x22
＝3300

1:3.6x42.3x3.75-12.5x0.423x28
=3.6*0.423*100*3.75-12.5*0.423*28
=0.423*(3.6*375-12.5*28)
=0.423*(4*9*12.5*3-12.5*4*7)
=0.423*[50*(27-7)]
=0.423*1000=423
2:19.58x66+22x91.26
=19.58*3*22+91.26*22
=(20-0.42)*3*22+(100-8.74)*22
=(60-1.26)*22+(100-8.74)*22
=(60+100-10)*22
=150*22
=3300