Hi there!
For each of these problems, I'm going to be using the formula for the area of a circle, which is A = pi x r^2. All you have to do is plug in the numbers and solve.
1. A = 3.14 x 4^2
A = 3.14 x 16
A = 50.24mm^2 - option 3
2. A = 3.14 x 9^2
A = 3.14 x 81
A = 254.34cm^2 - option 2
3. Find area and divide by how many feet each flower needs, which is 2.
A = 3.14 x 7^2
A = 3.14 x 49
A = 153.86/2
Flowers = 77 - option 3
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!