You can multiply or divide one equation so that it has a variable with a coefficient opposite of the other equation.
Example:
A) 2x + 3y = 6
B) 4x +2y = 20
Notice that neither equation has a "1" or "-1"
Let's multiply Equation A) by -2
A) -4x -6y = -12 Then add it to B)
B) 4x +2y = 20
-4y = 8
y= -2
A) 2x + 3*-2 = 6
2x = 12
x = 6
