Find the total number of tiles needed to tile the room

Minh's famly need to tile the floor of a rectangular room with square tiles.The lenght of the side of each tile is 0.35 m.The perimeter of the room is 34 m,ít width is 3m less than ít lenght.Each of the tiles close to the wall, if not a whole one ,is cut from a whole tile.
a)Find the total number of tiles needed to tile the room.
b) Each tile cost $7,how much does it cost to tile the room?