解x 过程详细 x*0.12+(30-x)*0.14=4

问题描述:

解x 过程详细 x*0.12+(30-x)*0.14=4

x*0.12+(30-x)*0.14=4
0.12x+30*0.14-0.14x=4
0.14x-0.12x=4.2-4
0.02x=0.2
x=0.2÷0.02
x=10