Question 775789
The total cost for the first year is
$4.95 + (12-1)($18.95) = $4.95 + 11($18.95) = $4.95 + $208.45 = $213.40
Up to there, the question is a "word problem" that any fifth grader should solve easily.
 
Beyond that, the question turns into a mind-reader's puzzle.
What is {{{a[1]}}} and what is {{{d}}}?
Usually those terms refer to an arithmetic sequence, but what arithmetic sequence do you have in mind (or what does the teacher have in mind)?
Why does the problem make you/anyone think of arithmetic sequences?
What is gained from viewing the problem as an application of arithmetic sequences?
 
Maybe you (and/or the teachers who want contrive this as an application of arithmetic sequences) are thinking of
{{{a[n]}}}= total cost for the first {{{n}}} months.
In that case,
{{{a[1]="$"}}}{{{4.95}}} is the cost for the first month
{{{d="$"}}}{{{18.95}}} is the monthly charge for each additional month.
{{{a[n]="$"}}}{{{4.95+(n-1)18.95}}} is the total charge for the first {{{n}}} months, and
{{{a[12]="$"}}}{{{4.95+(12-1)18.95}}} is the total charge for the first {{{12}}} months (the first year) as calculated above.
That is probably the expected answer. 
 
A different arithmetic sequence I could relate to this problem is
{{{a[n]}}}=total cost for the first {{{n}}} years.
In that case,
{{{a[1]="$213.40"}}} is the cost for the first year as calculated above,
{{{d="$"}}}{{{18.95*12="$227.40"}}} is the total cost for each additional year, and
{{{a[n]="$213.40+$227.40"(n-1)}}} is the total charge for the first {{{n}}} years.