Which of the coordinates listed below could represent a point found on the line 3x?

Well.. You seem to have forgotten to add the coordinates...

Anyway, the line is represented by the function f(x) = 3x .

Any point which follows the form (x,3x) will be on the line

for example (-3,-9) ; (-2,-6) ; (-1,-3) ; (0,0) ; (0.333333,1) ; (1, 3) ; (2,6) ; (3,9) ; and so on