2个未知数,1个方程,有无数组解.
[2x×(30-y)]-(30x)=1/5,【5分之1】?
60x-2xy-30x=1/5
30x-2xy=1/5
150x-10xy=1
(150-10y)x=1
x=1/(150-10y),
y=1,x=1/140;
y=2,x=1/130;
...