Final answer:
By substituting the side length of 3 feet into the formula c = 25s^2, we find that Ricardo will pay $225 for the square sheet of glass.
Step-by-step explanation:
To find the cost c of a square sheet of glass using the formula c = 25s^2, where s represents the length of a side in feet, we substitute the given side length of 3 feet into the formula:
- s = 3 feet
- c = 25 × (3 feet)^2
- c = 25 × 9 square feet
- c = 225 dollars
Therefore, Ricardo will pay $225 for a square sheet of glass that is 3 feet on each side.