Answer:
7 and a half cans of Paint ( 7.5 cans of paint )
Explanation:
If one can of paint covers 400 square feet then this should be easy. Since you need 3,000 square feet covered with paint (and one paint can cover 400 sq) then just divide 3,000 by 400.
This will show you how many times 400 can go into 3,000 which is the same as saying "how many cans of paint can i used to cover 3,000 square feet?"
Hope this helped!
-Greg