3x+12y=-66;2x-5y=21 by substitution, elimination, cross multiplication,and garapically methods
the first can be reduced to x + 4y = -22
or x = -4y - 22
It is now perfect for substitution
sub into the 2nd:
2(-4y-22) - 5y = 21
-8y -44 - 5y = 21
-13y = 65
y = -5
sub into x = ...
x = -4(-5) - 22
x = -2
for elimination:
x + 4y = -22
2x - 5y = 21
I would multiply the first be -2, and then add
etc
Did you learn the steps to solve by "cross multiplication" ?
Sounds like the old method using determinant
Graphing it not easy to show here, google "solve equations by graphing"