Given that Verizon charges a base fee of $20 per month plus an additional charge for each minute the customer uses. The monthly phone cost, C, can be represented with the equation C = 20 + a(m), where a is the additional charge per minute, and m is the number of minutes used.
We have to find the equation that can be utilized to find the number of minutes a customer used if we know a and C.
Now, we have to solve for m:
![\begin{gathered} C=20+am \\ C-20=20+am-20 \\ C-20=am \\ (C-20)/(a)=(am)/(a) \\ (C-20)/(a)=m \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/ev4gtk1gzezzs0hzzyaep5l2beggyy0e0i.png)
Thus, option A is correct.
2nd part:
Given that Alicia paid $30 and used 500 minutes.
So, the value of C is 30 and m = 500. So,
![\begin{gathered} C=20+am \\ 30=20+a(500) \\ 30-20=500a \\ 10=500a \\ (10)/(500)=a \\ 0.02=a \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/3yt9dh8yooyorawmrsbqxvyvcr82maowey.png)
Thus, the additional charge per minute is $0.02 per minute.