Explanation:
When drawing the scale factor of 3, you times all the sides by 3. For example for A, the top line is 2 boxes, so when enlarged the top line will be 6 boxes, and you would do this for the whole shape. (I would recommend doing the diagonal last). Same principal for scale factor of 1/2, you would divided all the sides by 2. For example, for C, the bottom line is 6 boxes, after the enlargement it will be 3 boxes long.