Question 17
A $5 \times 7$ table has one red cell and all other cells white. On this table we place tiles of the shape 
(a tile may be reflected or rotated) so that they lie entirely on the table. Tiles may overlap on the red cell, but not on white cells. Determine all possible positions of the red cell for which the table can be completely covered.
(a tile may be reflected or rotated) so that they lie entirely on the table. Tiles may overlap on the red cell, but not on white cells. Determine all possible positions of the red cell for which the table can be completely covered.