x/12+20-x/3=x/4+30-x/5

问题描述:

x/12+20-x/3=x/4+30-x/5

两边乘60
5x+20(20-x)=15x+12(30-x)
5x+20*20-20x=15x+12*30-12x
400-15x=3x+360
15x+3x=400-360
18x=40
x=40÷18
x=20/9