{x+2y=9 {y-1=3x

{x+2y=9 {y-1=3x x=9-2y** y-1=27-6y* * 7y=28 y=4 ** x=9-8 x=1

x+2y=9 y-1=3x x=9-2y y-1=3*(9-2y) y-1=27-6y y+6y=27+1 7y=28 /:7 y=4 x=9-2y x=9-2*4 x=9-8 x=1

x+2y=9 y-1=3x x=9-2y y-1=3*(9-2y) y-1=27-6y y+6y=27+1 7y=28 /:7 y=4 x=9-2y x=9-2*4 x=9-8 x=1