1﹚0.4×5／0.4×5
=0.4×5÷0.4÷5
=1
2﹚2.65×1.7+8.35×1.7-1.7
=﹙2.65+8.35-1﹚×1.7
=10×1.7
=17
3﹚3.91／﹙22-19.7﹚
=3.91÷2.3
=1.7
4﹚﹙6-10.88／3.2﹚×1.5
=﹙6-3.4﹚×1.5
=2.6×1.5
=3.9