The profit is represented by the following function:
[tex]\begin{gathered} f(n)=1.25n-15 \\ \text{where:} \\ n=\text{Number of bracelets sold} \end{gathered}[/tex]Lucy sold 25 bracelets last month, so:
[tex]\begin{gathered} n=25 \\ f(25)=1.25(25)-15=31.25-15=16.25 \end{gathered}[/tex]