Hey guys could someone help me out with this?

Answer:
3.33km
Step-by-step explanation:
Multiply 12 by 5
=60
60km^2 is one layer of 12x5km, so every 60 square kilometers is one layer.
Keep adding layers until you're as close as can be to 200.
You'll end up with 3 layers and 20 more square kilometers.
20 is one-third of 60, so your answer is 3 1/3, or 3.33km^2