To solve this problem we have to formulate an equation that models it. We identify that our variable is the weeks w and that the initial value we have to gather the total value of the bike is 60, so
[tex]\begin{gathered} w\to\text{week} \\ w_0=60 \\ Bike=125 \\ Increase=5 \end{gathered}[/tex][tex]Bike=w_0+increase\cdot w[/tex][tex]125=60+5w[/tex][tex]\begin{gathered} 125-60=5w \\ 65=5w \\ w=\frac{65}{5} \\ w=13 \end{gathered}[/tex]