Let's solve your system by substitution.
y
=
−
3
x
−
4
;
3
x
+
y
=
2
Step: Solve
y
=
−
3
x
−
4
for y:
y
=
−
3
x
−
4
Step: Substitute
−
3
x
−
4
for
y
in
3
x
+
y
=
2
:
3
x
+
y
=
2
3
x
+
−
3
x
−
4
=
2
−
4
=
2
(Simplify both sides of the equation)
−
4
+
4
=
2
+
4
(Add 4 to both sides)
0
=
6