The equation given is:
[tex]C=3p+1.75[/tex]Where C is the cost an p is the number of boxes of popcorn.
Since, it is given that the total cost is 9.25, we put it into "C" and solve for "p", the number of boxes of popcorn bought.
Hence,
[tex]\begin{gathered} C=3p+1.75 \\ 9.25=3p+1.75 \\ 9.25-1.75=3p \\ 7.5=3p \\ p=\frac{7.5}{3} \\ p=2.5 \end{gathered}[/tex]p = 2.5
