I'm pretty sure its 16 boxes of vegetables that she had taken home because u subtract the 80 boxes of potatoes with the 71 boxes that she had sold then thats 9 boxes of potatoes. U then subtract the 75 boxes of carrots with the 68 boxes of carrots to get 7 boxes of potatoes left. So finally, you add the 9 boxes of potatoes of carrots with the 7 boxes of potatoes to get 16 boxes of vegetables that she had taken home.
When u have an exponential functions with a number between 0 and 1, the curve is decreasing. it would approach 0, but the -2 at the end which shift the whole thing down 2, so it would approach -2 instead