解方程组{x-y=48...① 6(0.9x-y)=9(x-30-y)...②

2个回答

  • 解析:

    {x-y=48...①

    {6(0.9x-y)=9(x-30-y)...②

    ②式可化为:

    2(-0.1x+x-y)=3(x-y-30)

    将①式代入上式可得:

    2(-0.1x+48)=3(48-30)

    2(-0.1x+48)=3*18

    -0.1x+48=27

    0.1x=21

    解得x=210

    代入①式,可得:

    210-y=48

    解得:y=162

    所以原方程组的解为:

    { x=210

    { y=162