Write a piecewise function that models each telephone billing plan. Then graph the function.

$60 per month buys 450 minutes. Additional time costs $0.35 per minute.

Answer: if 0 < x ≤ 450, y = $60.

if 450 < x; y = $60 + (x - 450min) * $0.35

Step-by-step explanation:

Here x will represent the number of minutes.

with $60 you have 450 minutes, and you must pay 60 regardless of how much minutes you use.

so if 0 < x ≤ 450, y = $60.

now, if you call for more than 450 minutes, you get an additional of $0.35 per minute, then we have:

if 450 < x; y = $60 + (x - 450min) * $0.35

where we use (x - 450) * $0.35 because any minute after the 450 minute mark is considerated an additional time.

So our piecewise function is:

if 0 < x ≤ 450, y = $60.

if 450 < x; y = $60 + (x - 450min) * $0.35