What is not clear to me is: does the array have only positive numbers or are you finding the average of only positive numbers?

If the first, then Ancient Dragon has the con
If the second, you'd need to pull out only the positive numbers and divide by their count.

Perhaps ...
int a[6] = {2,-3, 4, -5, 6, -7};

int b[6] = new int[];
loop through a, placing positive values in b
then ...
The sum is 2+4+6 = 12
The average is 12/3 = 4