What is the fornula for find arithemetic ewuation​

a_{n} = a_{1} + (n-1)d

a_n=the nᵗʰ term in the sequence

a_1=the first term in the sequence

d=the common difference between terms

The general term of an arithmetic sequence can be written in terms of its first term a1, common difference d, and index n as follows: an=a1+(n−1)d. ... The nth partial sum of an arithmetic sequence can be calculated using the first and last terms as follows: Sn=n(a1+an)2.

the answer is d. 75%