解方程数学题① 0.3（y-2)=1-(x+1)/5②(0.04x+0.09)/0.2-(0.1y-0.3)/0.4=1.5呃.这是个二元一次方程组,打得不好将就着看吧.

原方程组化为2x+3y=14,4x-5y=6.解这个 方程组得x=4，y=2

1、0.3（y-2)=1-(x+1)÷5
0.3y-0.6=1-x÷5+0.2
0.3y=1+0.6-x÷5+0.2
0.3y=1.6+0.2-x÷5
0.3y=1.8-x÷5
y=1.8-x÷5÷0.3
y=1.8-x÷1.5
y-1.8=－x÷1.5
y+x=1.8÷1.5
y=2
x=4

从1解出x或y然后代入2即可

0.3y-0..6=1-0.2x-0.2
0.02x+0.45-0.25y+0.75=1.5
y=2 x=4

1、0.3（y-2)=1-(x+1)÷5
0.3y-0.6=1-x÷5+0.2
0.3y=1+0.6-x÷5+0.2
0.3y=1.6+0.2-x÷5
0.3y=1.8-x÷5
y=1.8-x÷5÷0.3
y=1.8-x÷1.5
y-1.8=－x÷1.5
y+x=1.8÷1.5
y=2
x=4

0.3y-0.6=0.8-0.2x
0.2x+0.45-0.25y+0.75=1.5
0.2x+0.3y-1.4=0
0.2x-0.25y-0.3=0
0.55y=1.1 y=2
代入 x=4

1-0.3(y-2)=x+1/5
两边同乘以5
5-1.5（y-2）=5x+1
5-1.5y+3=5x+1
5x+1.5y-7=0