[x+(x-2.4)]*2=80怎么解
问题描述：
[x+(x-2.4)]*2=80怎么解
答
[x+(x-2.4)]*2=80
(2x-2.4)*2=80
2x-2.4=80/2
2x-2.4=40
2x=40+2.4
2x=42.4
x=42.4/2
x=21.2