Answer: f(x) = 0.30x + 2.50
This is the same as writing y = 0.30x + 2.50
========================================================
Step-by-step explanation:
x = number of pounds
y = f(x) = total cost in dollars
1 pound costs $0.30
x pounds cost 0.30x
This is ignoring the entrance fee
Tacking on the entrance fee leads to a total of y = 0.30x + 2.50
------------------
The independent variable is always x and the dependent variable is always y.
The independent variable (number of pounds) determines what the dependent variable (total cost) will be.