Answer: The correct option is (C) 660 ft².
Step-by-step explanation: Given that Carlos is building three gardens, each the same size, in his backyard. Each garden is in the shape of a square with a 3 foot by 3 foot section removed from each of the four corners.
One of the gardens is shown in the given figure.
We are to find the total area of all three gardens.
The area of the section removed from the four corners of aech garden is given by
[tex]R_s=4\times 3\times 3=36~\textup{ft}^2.[/tex]
Therefore, the total area of one garden will be
[tex]G=16\times 16-36=256-36=220~\textup{ft}^2.[/tex]
Since there are three gardens, so the total area of the three gardens is given by
[tex]G_t=3\times G=3\times 220=660~\textup{ft}^2.[/tex]
Thus, the total area of the three gardens is 660 ft².
Option (C) is CORRECT.