15/23*19+19/23*8
=19/23*15+19/23*8
=19/23*(15+8)
=19/23*23
=19
12÷［(4.3-2.38)*25］
=12÷[(4.3-2.38)*25]
=12÷(1.92*25)
=12÷(12*0.16*25)
=1÷(0.16*254
=1÷4
=1/4为什么=19/23×15+19/23×815/23*19 =(15*19)/23 =19/23*1512÷［(4.3-2.38)*25］===?第三个不懂1.92=12*0.16