Answer:
-6
Step-by-step explanation:
2n can be the smallest integer, and 2n + 18 will be the largest integer.
The sum of this, divided by two, will result in the average/mean.
(2n + 2n + 18)/2 = 3
Multiply each side by 2:
(2n + 2n + 18)/2 ⋅ 2 = 3 ⋅ 2
2n + 2n + 18 = 6
Combine the like terms:
4n + 18 = 6
Subtract 18 from both sides:
4n + 18 - 18 = 6 - 18
4n = -12
Divide each side by 4:
4n/4 = -12/4
n = -3
Since we decided to go by 2n:
2n = 2(-3) = -6