input: Write a python function to check if a number is divisible by both 3 and 5.
  assert check_divisible_3and5(15) == True
  assert check_divisible_3and5(30) == True
  assert check_divisible_3and5(10) == False
  assert check_divisible_3and5(9) == False
output: def check_divisible_3and5(n):
      return n % 3 == 0 and n % 5 == 0