4/5+8*0.45
=0.8+0.8x4.5
=(1+4.5)x0.8
=5.5x0.8
=4.4为什么1+4.5呢？1哪里来的4/5+8*0.45 =0.8+0.8x4.5 =1x0.8+0.8x4.5 =(1+4.5)x0.8 =5.5x0.8 =4.4 祝学习进步，望采纳~~那个1是根据题外加的，对吗？不是 0.8=0.8x1 也算是题外加的吧