SOLUTION:
Algebra.Com
Question 6327:
Answer by IA(6) (Show Source): You can put this solution on YOUR website!
this problem cannot be solved by the addition method in order to cancel the -6y you must subtract one equation from the other
x-6y=33
8x-6y=54
8x-6y=54
x-6y=33
7x=21
x=3