解线性方程组（多元一次）,水平有限，DOS界面。其中，输出方程组的未知数用x1,x2,x3...表示，可以解出多元一次方程。-Solution of linear equations (multi-time), is limited, DOS interface. Among them, the output equations with unknowns x1, x2, x3 ..., said multi-linear equation can be solved.