Well, first you must find the total amount of tiles that Augustin needs to paint.
So, 300 from the bathroom
675 from the kitchen
+ 100 from the hallway
--------------------
All together, 300+675+100=1075.
Because each can covers 450 tiles, and you are trying to find how many cans you Augustin needs, you woud divide 1075 by 450.
1075/450 is 2.38888888 is not a full number, and you can not have part of a can. You also would not round downward, because then you wouldn't paint all the tiles. Therefore, you would round upward to 3.
Augustin will need 3 cans of paint.
