Can anyone solve this by elimination?
10x + y=-30
-10x - 4y= 30

Step: Solve
10
x
+
y
=
−
30
for y:
10
x
+
y
=
−
30
10
x
+
y
+
−
10
x
=
−
30
+
−
10
x
(Add -10x to both sides)
y
=
−
10
x
−
30

Step: Substitute
−
10
x
−
30
for
y
in
−
10
x
−
4
y
=
30
:
−
10
x
−
4
y
=
30
−
10
x
−
4
(
−
10
x
−
30
)
=
30
30
x
+
120
=
30
(Simplify both sides of the equation)
30
x
+
120
+
−
120
=
30
+
−
120
(Add -120 to both sides)
30
x
=
−
90
30
x
30
=
−
90
30
(Divide both sides by 30)
x
=
−
3

Step: Substitute
−
3
for
x
in
y
=
−
10
x
−
30
:
y
=
−
10
x
−
30
y
=
(
−
10
)
(
−
3
)
−
30
y
=
0