3.9/(1.3*5)=3.9÷1.3÷5=3÷5=0.6
3.8*43.7+4.12*38+151*0.38
=3.8*43.7+3.8*41.2+3.8*15.1
=3.8*（43.7+41.2+15.1）
=3.8*100
=380
40*5%/20%+40
=40*1/4+40
=40*(1/4+1)
=40*(5/4)
=50
几道六年级数学简算题,速速速速~~~~~~~~~~~~~~~~~~~~
3.9/(1.3*5)=3.9÷1.3÷5=3÷5=0.6
3.8*43.7+4.12*38+151*0.38
=3.8*43.7+3.8*41.2+3.8*15.1
=3.8*（43.7+41.2+15.1）
=3.8*100
=380
40*5%/20%+40
=40*1/4+40
=40*(1/4+1)
=40*(5/4)
=50