6.9+ 4.8 +3.1=(6.9+3.1)+4.8=14.8
32 +4.90.9+6.9 +4.8 +3.1=34.9-0.9+(6.9+3.1)+4.8=34+10+4.8=48.8
9.1=1.3x7.4.8=1.6x3.0.5=0.25x2 原算是式=7x1.3/1.3x3x1.6/1.6x2x0.25/0.25 =7x3x2=42
6.9+4.8+3.1=(6.9+3.1)+4.8=10+4.8=14.8
是这样的:48x0.69+3.1x4.8 =(0.69+3.1)x48x4.8 =1x48x4.8 =48x4.8 =230.4
4.8加上2.7乘以3.1=4.8+0.37=13.17 没有合适的简便方法 直接计算
48X0.69+3.1X4.8 =48X0.69+0.31X48 =48X(0.69+0.31) =48X1 =48
4.8*2.9+3.1*4.8-2.4*2=4.8x(2.9+3.1-1)=4.8x5=24
48*0.69 +3.1*4.8= 48*0.69+0. 31*48=48*(0.69+0.31)=48*1=48
48*0.69+3.1*4.8=48*0.69+48*0.31=48*(0.69+0.31)=48