after 5 moths Joe and Bill will have paid the same amount
Explanation
Step 1
Joe paid $100 to join a health club and $50 a month to use the club
let
x represents the number of months
then
after x months joe has paid:
[tex]\text{total}=100+50x[/tex]Now, for Bill
Bill paid nothing down to join the health club and $70 a month to use the club
after x months bill has paid:
[tex]\text{total}_b=70x[/tex]Step 2
months will they have paid the same amount of money
it menas total 1= total 2
[tex]\begin{gathered} \text{total}_j=total_{bi} \\ 100+50x=70x\text{ equation(1)} \end{gathered}[/tex]Step 3
solve the equation
[tex]\begin{gathered} 100+50x=70x \\ \text{subtract 50x in both sides} \\ 100+50x-50x=70x-5x \\ 100=20x \\ \text{divide both sides by 20} \\ \frac{100}{20}=\frac{20x}{20} \\ 5=x \end{gathered}[/tex]so, the answer is
after 5 moths Joe and Bill will have paid the same amount