Hey dino. I'm assuming you want the # of carrots left to change as the player puts carrots in the box, right?
You'll need a separate variable to track the difference between the # of carrots needed and the # in the box, re-calculating whenever a carrot is put in the box (or every tick, if that's easier). Right now, you don't have a variable that tracks the changing "# of carrots needed".
You'll also need to change the # that's displayed to match the number of carrots left. Because you use images, that could be a a lot of work; you are moving images into and out of the layout during the game. It might be better to put all the # images into a single animation and just change the animation frame to match the # of carrots remaining.
I can see how that was frustrating! It took me a while to locate the problem; sometimes we are blind to our own work.
Take care, dino, and let me know how it goes!
Edit: Let me know if you'd like some help and I'll work on making the changes suggested. I'm using the latest build (r111, I think).