Answer:
D. 3
Step-by-step explanation:
Assuming the model represents an equation, the following can be deduced:
On the left side of the equation, the model shows we have 3 "x's", and 6 "1's". Let this represent:
3x + 6
On the right side of the equation, we have 2 "x's" and 9 "1's". Let this represent:
2x + 9.
The model would represent the equation below:

Solve for x
(Subtracting 2x from both sides of the equation)

(subtracting 6 from both sides of the equation)

Subtract 9 from both sides
b = -12 - 9
simplify -12 - 9
Answer: b = -21
9 + -21 = -12 is true.
simplify brackets
simplify q + -9 to q - 9
add 9 to both sides
simplify 12 + 9 to 21
q = 21
21 + -9 = 12 is true.
Solution: Check the picture I uploaded.
The answer would be the square root of 25 times 9 im pretty sure its been while and it would be 25*9=225 square root of 225 is 15