3x+2y=7
5x-y=2 /·2
----------------
3x+2y=7
10x-2y=4
--------------- (+)
13x=11
x=11/13
3· 11/13 + 2y= 7
33/13+2y=7
2y=7-33/13
2y=(91-33)/13
2y= 58/13
y=58/26
y=29/13
b) 2x+y=1 /·2
x-2y=-1
----------------
4x+2y=2
x-2y=-1
-----------------(+)
5x=1
x=1/5
2· 1/5+y=1
2/5+y=1
y=1 -2/5
y=3/5