Hi! You are on the right track! Let's focus on the first two first:
1. Bill wrote the number 36,721. Tom wrote the number 45,378. How many times greater is 7 in Bill's number than Tom's number.
You wrote 10, which is RIGHT! The 7 in Bill's number is in the hundreds (700), while the 7 in Tom's number is in the tens (70). 700 is 10 times 70.
2. Sarah wrote the number 13,285. Then Bill wrote a 5 digit number that only had one 3 in it. The 3 in Bill's number is worth 10 times as much as the 3 in Sarah's number. Write what 5 digit number Bill could have written.
Now, you started to write out...30,_ _ _ which is on the right track! The 3 is in the right place. Sarah's 3 is in the thousands (3,000), so Bill needs to write a 3 which is in the tens of thousands (30,000).
Now, we know that there is only ONE 3 in Bill's number, and he already wrote it down. The key word in the problem is COULD. So there is more than one answer to this problem! You just need to fill in the rest of the blanks with any number that is NOT a 3. Make sense?