To find the length of the room in the drawing, we can use the scale given:
1 inch = 4 feet.
If the actual length of the room is 20 feet, we can use the following steps to find out how long that is in the drawing:
\[ \text{Length in drawing (inches)} = \frac{\text{Actual length (feet)}}{\text{Scale factor (feet per inch)}} \]
In this case:
\[ \text{Length in drawing} = \frac{20 \text{ feet}}{4 \text{ feet/inch}} = 5 \text{ inches} \]
Thus, the length of the room in the drawing is 5 inches.