All the presented numbers are not decimal number, because thay don't have decimal places, so all of them are integers.
Every number without a negative number appart from 0 is a positive number, so -3, -1 and -15 are not positive integers. Also, 0 is neither positive nor negative, so even though it don't have a negative sign it is not positive.
So, the only positive integers of the list are +5, 7 and +11.