7.2+2.8除4=7.2+0.7=7.90.25×3.2×1.25 简便计算=0.25x0.4x8x1.25=(0.25x0.4)x(8x1.25)=0.1x10=1
7.2+2.8÷4 =7.2+0.7=7.90.25×3.2×1.25=0.25X4X(0.8X1.25)=1X1=1