Let "x" represent the number of months
Firness Club A charges $28 to join and then $18 each month, you can express the total cost as an equation:

Fitness Club B cherges $35 to join and $11 each month, you can express the total cost as an equation:

You need to know the amount of month needed for both clubs to cost the same:

From the equation determined you can calculate the value of x:

After one month the total cost of each club will be the same.