For this all you have to do is plug in the x and y values into the equation and see if it is a true statement. If it's true then it's on the line. The x value is 2 and the y is -4.
12x + 3y = 6
12 (2) + 3 (-4) = 6
24 -12 = 6
12 = 6
The statement 12=6 is not a true statement so that point is not on the line.