Tonya plans to join a fitness club. She researched the costs to join different clubs in her area and found that there is a linear relationship between the total cost of belonging to a club and the number of months that you are a member. Each club charges monthly dues, and some clubs require new members to also pay a one-time membership fee. The total costs of being a member for 6 months, 12 months, and 24 months at each of three clubs are shown in the table. Total Cost of Fitness Club Membership
Length of membership
Club 1
Club 2
Club 3
6 months
$108
$120
$126
12 months
$216
$210
$252
24 months
$432
$390
$504

How many of the clubs require new members to pay a one-time membership fee?