To represent the total cost \( y \) based on the number of months \( x \) for a gym membership, you can use the following equation:
\[ y = 24x + 88 \]
In this equation:
- \( 24x \) represents the monthly cost, which is $24 per month multiplied by the number of months \( x \).
- \( 88 \) is the one-time registration fee.
So, the total cost after \( x \) months is given by this equation.