What you know:
Mr. Adams spent $36.25 on 12.5 pounds.
All you do to find the cost per each pound is:
36.25/12.5
Your answer:
$2.9 dollars per pound.
Hello,
........|x^4|x^3|x^2|x^1|x^0
........| 1..|.2...|.-9.|.-2.|.8
x=-3.| ....|.-4..|.8..|.4..|.-8
........| 1..|.-2..|.-1.|..2.|.0
x^4+2x^3-9x^2-2x+8=(x+3)(x^3-2x^2-x+2)+0
-4 is a root of the polynomial expression.