Answer:
3480
Explanation:
Set it up so it looks like this.
(2580 + 2930 + x )/3 = 3000 Combine the terms on the left
(5510 + x) / 3 = 3000 Multiply by 3
5510 + x = 9000 Subtract 5510
x = 9000 - 5510
x = 3490
Does that really work?
2580 + 2930 + 3490 = 9000
Which says it does work.