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:
[tex]C_A=28+18x[/tex]Fitness Club B cherges $35 to join and $11 each month, you can express the total cost as an equation:
[tex]C_B=35+11x[/tex]You need to know the amount of month needed for both clubs to cost the same:
[tex]\begin{gathered} C_A=C_B \\ 28+18x=35+11x \end{gathered}[/tex]From the equation determined you can calculate the value of x:
[tex]\begin{gathered} 28+18x=35+11x \\ 18x-11x=35-28 \\ 7x=7 \\ x=1 \end{gathered}[/tex]After one month the total cost of each club will be the same.