x
=
−
3
y
=
5
Explanation:
I would multiply the first equation by
−
4
and the second by
3
and add together the two equatins (in columns):
{
−
12
x
−
28
y
=
−
104
{
12
x
+
15
y
=
39
0
−
13
y
=
−
65
So:
y
=
65
13
=
5
Substitute back this value into the first equation:
3
x
+
7
⋅
5
=
26
3
x
=
26
−
35
=
−
9
x
=
−
9
3
=
−
3
