Let's plot the po

In a graph the horizontal line is x-axis, and the vertical line is y-axis, and the point of intersection of x and y-axis is the origin (0,0).

So at any point the first number if x-coordinate and the second number is y-coordinate.

For (1, 1) move 1 unit in x-direction and 1 unit in y-direction.

For (3,7) move 3 unit in x-direction and 7 unit in y-direction.

For (9,1) move 9 unit in x-direction and 1 unit in y-direction.

For (12,1) move 12 unit in x-direction and 1 unit in y-direction.

So the graph of the given points is as shown below.

From the above graph we can see that point (1,1), (9,1) and (12,1) lie on a single line.