The unknown is how many girls and boys are in the class.
Answer:

Step-by-step explanation:
I attached an image to aid the understanding of the question.
Looking at the image, we see that the 8 shaded parts are congruent, as affirmed in the question as well. And we are told that T = 3, this implies that the area of the square with T as it's side is 9ft². Since all the 8 squares are congruenrt, it means each square has its area to be 9. Therefore, the total area of the 8 shaded squares will be:

It remains the area of the shaded square with side S.
From the question, we have the following ratio:
I did not add ± because length is always positive, so the case of negative is eliminated.
Now the areas of S is 
Therefore, the total area of the shaded squares is

Answer:
A. n = 5
Step-by-step explanation:
S = n² + n
When S = 30:
n² + n = 30
Subtract 30 from both sides: n² + n - 30 = 0
Factorize: (n - 5)(n + 6) = 0
Therefore n = 5 or -6
As n > 2, then n = 5 only
Answer:
0
Step-by-step explanation:
-20.5 is the same as -20.5
, since anything to the zero power is equal to 1.