You can put this solution on YOUR website! If you just add these two equations together, you will subtract out the x terms AND the y terms:
3x - 4y = 9
-3x + 4y = 12
0 + 0 = 21
Obviously this is NOT possible. There is NO way that 0 = 21! At least not in OUR lifetime!! This means that there is NO SOLUTION. Some textbooks will call this the Empty Set, and they write this either with empty set braces: { }, or with the Greek letter "phi" which is a 0 with a slash: . I personally think this is very confusing to students, so I prefer to just call it NO SOLUTION.
Now, think about what situtation could happen with equations of two straight lines that would cause a NO SOLUTION situation. What happened is that the lines are PARALLEL!!
