2x+3y=19 (1)
x+5y=1(2)
代入法
由(2)得x=1-5y
代入(1)
2(1-5y)+3y=19
2-10y+3y=19
2-7y=19
y=-17/7
x=1-5y=92/7
加减法
(1)-2*(2)
2x+3y-2(x+5y)=19-2*1
2x+3y-2x-10y=17
-7y=17
y=-17/7
(1)*5-(2)*3
5(2x+3y)-3(x+5y)=19*5-1*3
10x+15y-3x-15y=92
7x=92
x=92/7