She pays in total $1350 after the 12 months
Step-by-step explanation:
The given is:
1. Daniela borrowed some money from her parents she agreed to pay
 $30 at the end of the  first month
2. She agreed to pay $15 more each additional month for months
We need to find how much money she pays in total after the 12 months
The formula of the sum of n terms of an arithmetic series is
[tex]S_{n}=\frac{n}{2}[2a+(n-1)d][/tex], where a is the 1st term, d is the
common difference between each two consecutive terms, and n the
position of the term
∵ She will pay $30 at the end of the first month
∴ a = 30
∵ She will pay $15 more each month
∴ d = 15
∵ She will do that for 12 months
∴ n = 12
Substitute these values in the formula of the sum above
∴ [tex]S_{12}=\frac{12}{2}[2(30)+(12-1)15][/tex]
∴ [tex]S_{12}=6[60+(11)15][/tex]
∴ [tex]S_{12}=6[60+165][/tex]
∴ [tex]S_{12}=6[225][/tex]
∴ [tex]S_{12}=1350[/tex]
She pays in total $1350 after the 12 months
Learn more:
You can learn more about arithmetic sequence in brainly.com/question/7221312
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