Please help me do discrete mathematics, by including mathematical formulas for counting techniques

24. How many positive integers between 1000 and 9999 inclusive a) are divisible by 9? b) are even? c) have distinct digits? d) are not divisible by 3? e) are divisible by 5 or 7? f) are not divisible by either 5 or 7? g) are divisible by 5 but not by 7? h) are divisible by 5 and 7?