A new fast food restaurant opened 5 months ago. The table belows shows the number of burgers they've sold so far.
Month | Burgers Sold |
1 | 1,029 |
2 | 1,001 |
3 | 2,065 |
4 | 2,572 |
5 | 2,880 |
| 9,547 |
The next month (after spending some money on an ad) they sold 5 times as many as they had sold in the previous 5 months. How many fewer burgers did they sell before running the ad than they did after running it?