Answer:
x + 1, y * 2
Explanation:
We see that the first point is (2, 4). The point following (2, 4) is (3, 8). We see that to get to this point, we do 2 + 1 (x) and 4 * 2 (y). However, with this little information, we can't be sure that its x + 1, y * 2 or x + 1, y + 4. The next point (4, 16) confirms our hypothesis. 3 + 1 = 4 (x), and 8 * 2 = 16 (y).
Hope this helped.