Question

Store A sells lawnmower fuel for $4.00 per gallon.

Answer 1

StoreA
numbers greater than or equal to zero

Store B
numbers greater than or equal to zero
integer values only.

Store A sells by the gallon which is a continuous number so it can sell none or any numbers between 0 and infinity 

Store B sells per container so it can be 0 to infinity but only integer values, you cannot buy half of a container.