2x-3y-2=0 5x+3y=18 2x-3y=7 (2x-3y+5)/7+2y=9 2x-3y=3 6x+5y=35 解方程组,快

{2x-3y-2=0
{5x+3y=18 ,
解得{x=20/7,
{y=26/21.
2.{2x-3y=7 ,(1)
{(2x-3y+5)/7+2y=9(2)
把（1）代入（2）,12/7+2y=9,
y=51/14,
代入（1）,2x-153/14=7,
x=251/28.
3.{ 2x-3y=3 (1)
{6x+5y=35 ,(2)
(2)-(1)*3,14y=26,y=13/7,
代入（1）,2x-39/7=3,
x=30/7.