解：x÷5.5=125-5 x÷5.5=120 x=120*5.5 x=660
x/5.5=125-5x=120*5.5x=660所以未知数是660
125-x/5.5=5125-x/(55/10)=5125-x/(11/2)=5125-5=2x/112x/11=1202x=1320x=660
