1. The problem states a phone plan charges an initial fee of 40 plus 0.40 per minute. 2. We want to write a function $f(x)$ where $x$ is the number of minutes used, and $f(x)$ is the total cost. 3. The total cost is the initial fee plus the cost per minute times the number of minutes: $$f(x) = 40 + 0.40x$$ 4. This matches option (A) if we rewrite it as $f(x) = 0.40x + 40$. 5. Option (B) $f(x) = x^2 + 40$ is incorrect because the cost per minute is linear, not quadratic. 6. Option (C) $f(x) = 40(0.60)x$ is incorrect because it multiplies 40 by 0.60 and then by $x$, which does not represent the initial fee plus per minute cost. 7. Therefore, the correct function equation is option (A): $$f(x) = 0.40x + 40$$