Answer:
$18
Step-by-step explanation:
First, let's subtract the refistration fee of $15 from the total charge $231, so:
$231 - $15 = $216
Then, $216 will be paid monthly. So, to know how much they pay each month, we need to divide $216 by 12:
$216 ÷ 12 = $18
Therefore, new members pay $18 each month.