ANSWER:
a. trial plan
b. basic plan
c. 20 + 8n
d. 12n
STEP-BY-STEP EXPLANATION:
a.
We calculate the price in each case, like this:
[tex]\begin{gathered} p_b=20+8\cdot4=52 \\ p_t=12\cdot4=48 \end{gathered}[/tex]Therefore, if you go 4 times a month, the trial plan is better.
b.
We calculate the price in each case, like this:
[tex]\begin{gathered} p_b=20+8\cdot8=84 \\ p_t=12\cdot8=96 \end{gathered}[/tex]Therefore, if you go 8 times a month, the basic plan is better.
c.
Let n be the number of times you go per month, the cost expression of basic plan would be:
[tex]p_b=20+8n[/tex]d.
Let n be the number of times you go per month, the cost expression of the trial plan would be:
[tex]p_t=12n[/tex]