The area, $A = f(s)$ square feet, of a square wooden deck is a function of the side $s$ feet. Stain that costs $28.50 will cover 200 square feet of wood.

(a) Write the formula for $f(s)$.
$f(s) =$ help (formulas)

(b) Find a formula for $C = g(A)$, the cost in dollars of staining an area of $A$ square feet.
$C = g(A) =$ help (formulas)

(c) Find $C = g(f(s))$.
$C = g(f(s)) =$ help (formulas)

Which of the following best explains the meaning of the composite function $g(f(s))$?
A. The function for square feet and cost of stain.
B. The amount of stain to cover a square region of side length $s$ feet.
C. The cost to stain a square region of side length $s$ feet.
D. The cost to stain a region of area $A$ square feet.

(d) Evaluate and interpret, giving units.
$f(9) =$ ? feet square feet dollars dollars per foot dollars per square foot
$g(120) =$ ? feet square feet dollars dollars per foot dollars per square foot
$g(f(11)) =$ ? feet square feet dollars dollars per foot dollars per square foot