1)48*1.08+1.2*56.8=40*1.2*1.08+1.2*56.8=1.2*(43.2+56.8)=108 2)72*2.09-1.8*73.6=1.8*40*2.09-1.8*73.6=1.8*(83.6-73.6)=18
(1)、
48×1.08+1.2×56.8
=12×4×1.08+1.2×5.68×10
=12×4×1.08+12×5.68
=12×﹙4×1.08+5.68﹚
=12×﹙4.32+5.68﹚
=12×10
=120
(2)、
72×2.09﹣1.8×73.6
=18×4×2.09﹣1.8×7.36×10
=18×4×2.09﹣18×7.36
=18×﹙4×2.09﹣7.36﹚
=18×﹙8.36﹣7.36﹚
=18×1
=18
S