I take it that the point is (-4 , 1/2) that the comma was lost? I'll assume so.
Put minus 4 in for x. See what happens.
y = 1/2 ( - 4) - 4
y = -2 - 4
y = - 6
No this point is not on the line when you graph the line. You know because if you put x = - 4 you should get y = 1/2. Since you didn't, the answer is No. That's the acid test. Put the x value in of a point and solve.
If you get y, then the point is on the line.
Below is a graph of the line. Notice the point (-4,1/2) is not on the line. It is labeled as (-4,1/2) to your left.
