Explanation:

Let's calculate each percentage to determine the least value:

- 9% of 845:

- 9% of 845 is $0.09\times 845=76.05$

- 12% of 625:

- 12% of 625 is $0.12\times 625=75$

- 10% of 720:

- 10% of 720 is $0.10\times 720=72$

- 15% of 555:

- 15% of 555 is $0.15\times 555=83.25$

?? After these calculations, we can see that 10% of 720 is the least value.

So, the correct option is:

- Option 3: 10% of 720