简便① 3.6÷0.4-1.2X5 ②90÷（3.6-1.8）③（31.6-11.7）÷2.5÷0.4 ④3.4X7.8÷3.9 ⑤2.23X4+4.77÷0.25

① 3.6÷0.4-1.2X5
=9-6
=3
②90÷（3.6-1.8）
=90÷1.8
=90÷9÷0.2
=10×5
=50
③（31.6-11.7）÷2.5÷0.4
=（31.6-11.7）÷﹙2.5×0.4 ﹚
=19.9÷1
=19.9
④3.4X7.8÷3.9
=3.4×2
=6.8
⑤2.23X4+4.77÷0.25
=2.23X4+4.77×4
=﹙2.23+4.77﹚×4
=7×4
=28

① 3.6÷0.4-1.2X5 =1.2X（3÷0.4）-1.2X5 =1.2X（7.5-5 ）=1.2X2.5=0.3X（4X2.5）=0.3X10=3②90÷（3.6-1.8）=90÷1.8=5X（18÷1.8）=5X10=50③（31.6-11.7）÷2.5÷0.4 =（31.6-11.7）÷（2.5X0.4 ）=19.9÷1=19.9...