Dilation involves transformation. The result is either an enlargement or a reduction of the original image. This depends on the scale factor. If the scale factor is greater than 1, enlargement occurs. If the scale factor is lesser than 1, a reduction occurs. Looking at the given question, the scale factor is 1/2 which is less than 1 thus, a reduction occurs.
We would reduce each coordinate by 1/2. The coordinates of the image after dilation would be
J(-4 * 1/2, - 1 * 1/2) K(0 * 1/2, 4 * 1/2) L(- 4 * 1/2, - 2 * 1/2)
It becomes
J(- 2, - 1/2) K(0, 2) L(- 2, - 1)