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 | 2,904 |
2 | 1,585 |
3 | 3,097 |
4 | 1,775 |
5 | 2,195 |
| 11,556 |
The next month (after spending some money on an ad) they sold 7 times as many as they had sold in the previous 5 months. How many more burgers did they sell after running the ad?