x:七分之十=0.4x+12怎么解?

问题描述:

x:七分之十=0.4x+12怎么解?

x:10/7=0.4x+12
x=(0.4x+12)*10/7
x=4/7x+120/7
x-4/7x=120/7
3/7x=120/7
x=120/7*7/3
x=40