The scale of 1 to 50 tells us that each unit of length of the drawing represents 50 units of the length of the real bedroom. In other words, the drawing will be 50 times smaller than the real bedroom.
So, to find how wide the door should be on the scale drawing, we need to divide the real measure (0.8 m) by 50:
0.8/50 = 0.016
Therefore, the door on the scale drawing should be 0.016 m.