Please help me with number 3. I got about 25 but I don’t know if it’s correct.

Answer:
Step-by-step explanation:
1.8 * 10^12/ 8.1 * 10^10
25 is not a bad answer. When you do the division above, it comes to 22.22 repeating. Since you are saying about, I wouldn't mark it wrong. But I think my answer is closer to what they seek.