(12,-6)
When dilating points (or shapes) on a graph we simply multiply the x and y values in the coordinate. In this case we are given the point (4,-2). We then use the scale factor (the factor that we use to multiply the points by). The scale factor in this case is 3, where we multiply the x value and y value of (4,-2). 4*3=12 and -2*3=-6. Your new coordinate would then be (12,-6)
If you have any questions please feel free to comment on this.