atmhhns,你好:
1/3x+(8.1-x)*2/5=5/6x
解:1/3x+8.1*2/5-2/5x=5/6x
5/6x+2/5x-1/3x=8.1*2/5
9/10x=3.24
x=3.24÷9/10
x=3.6