解方程：5(x+3)-2(0.4x-1)=-2.5

5(x+3)-2(0.4x-1)=-2.5
解;去括号,得 5x+15-0.8x+2=-2.5
合并同类项,得 4.2x+17=-2.5
移项,得 4.2x=-19.5
方程两边同除以4.2 ,得 x=-19.5/4.2
即 x=-65/14

解:5(x+3)-2(0.4x-1)=-2.5
5X+15-0.8X+2=-2.5
4.2X=-19.5
X=19.5/4.2 (写成分数形式)

5x+15-0.8x+2=-2.5
4.2x+17=-2.5
4.2x=-19.5
x=-19.5/4.2

原式
5x+15-0.8x+2=-2.5
4.2x=-19.5
x=-195/42

5x+3*5+0.8=-2.5
5x=-2.5-0.8-15
5x=-18.3
x=-18.3/5
=-3.66

应该是x=-65/14