第一题:4.4×2.5＝（4+0.4）×2.5＝4×2.5+0.4×2.5＝10+1＝11第二种方法:4.4＝2.2×2所以，4.4×2.5＝2.2×2×2.5＝2.2×（2×2.5）＝2.2×5＝11
5x-12=8|5x-12+12=8+12、5x=20 5x÷5=20÷5 X=4
2/1x33x4x6/1
