The formula to calculate the amount of adhesive needed is:
\[ A = \frac{C}{CR} \]
Where:
Let's say the area to be covered (C) is 500 square feet and the coverage rate (CR) is 50 square feet per gallon. Using the formula:
\[ A = \frac{500}{50} \]
We get:
\[ A = 10\, \text{gallons} \]
So, the amount of adhesive needed for a 500 square feet area with a coverage rate of 50 square feet per gallon is 10 gallons.