To be a solution, (2,10) has to satisfy both equations....
-3x - 4y = 4
-3(2) - 4(10) = 4
-6 - 40 = 4
-46 = 4.....so (2,10) does not work here...no need to do the other equation because if it is not a solution in the first equation, then it is not a solution for the system of equations.
