Answer:
A coral reef grew 7 meters.
Explanation:
The prefix "milli" before any standard unit such as meters, grams, or seconds and etc., It means it takes 1000 milli units to make 1 standard unit. Example:
1 meter= 1 millimeters.
To solve this problem you need to cross multiply:
7000 millimeters 1 meter
multiply = 7 meters
1 month 1000 millimeters
Units that are the same and diagonal from each other cancel out.
So the answer is: Last month, A coral reef grew 7 meters.