Relative frequency of plastic buttons with four holes is 28/80 = 0.35
Relative frequency of plastic buttons with two holes is 15/80 = 0.1875
Relative frequency of wooden buttons with two holes is 34/80 = 0.425
Relative frequency of wooden buttons with four holes is 3/80 = 0.0375
0.35 + 0.1875 + 0.425 + 0.0375 = 1
9 is the blank.
(a+b)^2 = a^2 + 2ab + b^2
a = x
b = 3
(x+3)^2 = x^2 + 6x + 9
2+1/3n=8 is the answer, I believe.
-x^2 + 9 - 3x^2 - 11x + 4
-4x^2 - 11x + 13
