This game was pretty fun but I got to number 27 and it's exactly the same as 26 but the answer for 26 doesn't work. In addition, the hint mentions x and y, and the puzzle has no x/y table or graph or anything. That leads me to think that the developer forgot to change the picture to match the answer. Other than that, pretty good though.
Edit: after random trial and error, the answer is 98. No longer stuck. Changing from 3 to 4 stars