b - is a part of segment = 9.
We can see that
9 =b + x
b+x+b =12 -----> 2b + x =12
b +x=9 /*(-2) ------> -2b - 2x = -18
2b+x=12
-2b - 2x = -18
<u> 2b + x = 12</u>
-x = -6
x = 6
Do as the apples goes up in 4s
3 7 11 the goes 3 +4 = 7, 7+4 = 11
and Sees goes up in 40's
30 70 110
and rate of change is

its 40/4 or 10/1 (that's the first one)
First step: x= ± √ 121
Second step and correct answer: x= ± 11
Because: x^2 = x= ± √
C is the answer by using distributive property