11. As the number 11 there is only extended. If it is wrong, don't come blaming me!!
Answer: 4 or 
To find the square root of a number, remember that there will be two factors that are the same that will give you the product.
Lets start from 1:
1 x 1 = 1
2 x 2 = 4
3 x 3 = 9
4 x 4 = 16
As you can see, 4 x 4 is 16. To make sure I'm correct, remember that a square roots consists two identical factors.
4 and 4 are the same numbers.
Therefore,
= 4
It can also be written as 
Answer: (30m-9n)/270
First we start with m/9-n/30.
We multiply the denominators to get 270.
Then we multiply the numerators by the original denominators to get (30m-9n).
To check, we can use m=2, and n=4
2/9-4/30=4/45
(30*2-9*4)/270=24/270=4/45
C. Claire could be 6 foot 8 while Alice could be 5 feet.
D. It would be 3/4 to 4/4 because Alice is 1/4 shorter than Claire.
3/4 : 4/4 | 6/8 : 8/8 | 9/12 : 12/12 | etcetera.