﹙1﹚11×40+39×48+8×11
=﹙11×40+8×11﹚+39×48
=11×﹙40+8﹚×39×48
=11×48+39×48
=48×﹙11+39﹚
=48×50
=2400
﹙2﹚ 24×172-12×71×2-24
=24×172-24×71-24×1
=24×﹙172-71-1﹚
=24×100
=2400
﹙1﹚11×40+39×48+8×11
=﹙11×40+8×11﹚+39×48
=11×﹙40+8﹚×39×48
=11×48+39×48
=48×﹙11+39﹚
=48×50
=2400
﹙2﹚ 24×172-12×71×2-24
=24×172-24×71-24×1
=24×﹙172-71-1﹚
=24×100
=2400