8.4x4/11-4.2÷11/8+1.4÷1又2/5=8.4x4/11-4.2x8/11+1.4÷7/5=4.2x2x4/11-4.2x8/11+1.4x5/7=4.2x8/11-4.2x8/11+1=0+1=1望采纳，谢谢
