Hey there! I'm happy to help!
Since the tiles are square, all of their sides are the same. We see that one of the side lengths is 3/4. So, to find the area of the square, we square 3/4 (multiply it by itself)
3/4 × 3/4= 9/16
Therefore, the area of Sandy's tile is 9/16 square feet.
BONUS
We can also find the area of our floor, which is 9 feet by 10 feet, so it is 90. We can then divide by 9/16 to figure out how many tiles we need.
90/9/16=160
So, you would need 160 of these tiles to fill the floor.
I hope that this helps!