Question 217292
y=3x-12
y=4x+2  
You can either set these 2 equation equal to one another.
3x-12=4x+2
3x-4x=2+12
-x=14
x=-14 ans.
OR:
Multiply one of the equations by -1 & add them
-y=-3x+12
y=4x+2
-----------------
0=x+14
x=-14 ans.
y=3*-14-12
y=-42-12
y=-54 ans.