Answer :
x=2 is not the answer because when substituting 2 for x in both problems the answers are different.
-4(2)-12=-20
2(2)-8=-4
-20 does nothing equal to -4 which means x=2 is invalid
-4(2)-12=-20
2(2)-8=-4
-20 does nothing equal to -4 which means x=2 is invalid