Final answer:
The question cannot be answered without the original area of the air supply opening. The calculation involves determining the area with 100% opening and then finding 80% of that to get the area with the louvers fixed. The difference gives the additional area needed.
Step-by-step explanation:
The question pertains to calculating the additional area needed for an air supply opening if its louvers are fixed at 80% open. To calculate this, we would need the original area of the air supply opening. However, this information is not provided in the question. To solve a problem like this, you would typically determine the total area required for 100% airflow and then calculate 80% of that to find the fixed louver area. The difference between these two values would give you the additional area needed.
Since the necessary information to directly answer the question is absent, we cannot accurately calculate the additional square inches needed.