3道方程十

问题描述:

3道方程十
6x+4(20-x)=104
24-2(x-2)=70-6x
12+2(5x-7)=70-8x

1.6x+4(20-x)=104
6x+80-4x=104
2x=24
x=12
2.24-2(x-2)=70-6x
24-2x+4=70-6x
6x-2x=70-24-4
4x=42
x=10.5
3.12+2(5x-7)=70-8x
12+10x-14=70-8x
10x+8x=70-12+14
18x=72
x=4