**Solution:**

To determine which of the given numbers are divisible by 15, we need to check if they are divisible by both 3 and 5.

If the sum of the digits of a number is divisible by 3, then the number itself is divisible by 3. Therefore, we can check if the numbers are divisible by 3 by adding their digits.

To check if a number is divisible by 5, we only need to check if its last digit is 0 or 5.

Let's check each of the given numbers:

a) 73445: The sum of its digits is 7 + 3 + 4 + 4 + 5 = 23, which is not

divisible by 3, and its last digit is 5, which is divisible by 5. So, 73445

is not divisible by 15.

b) 38445: The sum of its digits is 3 + 8 + 4 + 4 + 5 = 24, which is

divisible by 3, and its last digit is 5, which is divisible by 5. So, 38445

is divisible by 15.

c) 39445: The sum of its digits is 3 + 9 + 4 + 4 + 5 = 25, which is not

divisible by 3, and its last digit is 5, which is divisible by 5. So, 39445 is not divisible by 15.

d) 64345: The sum of its digits is 6 + 4 + 3 + 4 + 5 = 22, which is not

divisible by 3, and its last digit is 5, which is divisible by 5. So, 64345

is not divisible by 15.

Therefore, only the number b) 38445 can be divided by 15.