Answer: 935 tons
Step-by-step explanation:
We'll add the last two values to get the amount dug this year.
2786+2862 = 5648
So the farmer dug 5648 tons of potatoes this year.
Subtract that result from the first value given
6583 - 5648 = 935
The farmer dug 935 more tons last year compared to this year.
In other words, the amount has dropped by 935 tons when going from last year to this year.