To model Giselle's account balance at the athletic club with a linear function, let’s define the variables:
- Let \( b \) be the balance in her account.
- Let \( x \) be the number of times she uses the club.
Giselle starts with $240 in her account, and each time she uses the club, $5 is deducted. Therefore, the function that represents her account balance can be formulated as:
\[ b = 240 - 5x \]
This means that her initial balance is $240, and for each visit (each time she uses the club — represented by \( x \)), $5 is subtracted from her balance.
So, the correct linear function that models the situation is:
\[ b = 240 - 5x \]