a)
To solve for n, we gotta take n to one side and everything else to another, like this:
![\begin{gathered} C=15n+75 \\ 15n=C-75 \\ n=(C-75)/(15) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/um9u5pjjnni6d21d54f55zdp09nvhy7ai3.png)
b)
Given a budget of 225 dollars, it means C = 225.
We need to figure out n, which we already have (the formula) from part (a) above.
So, let's use that and plug in C = 225.
Thus:
![\begin{gathered} n=(C-75)/(15) \\ n=(225-75)/(15) \\ n=(150)/(15) \\ n=10 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/gy5w541tr2cdg7ps9enbo3au4si2hl1dsv.png)
Thus, she can take 10 campers