Consider the following equation for the sum of a finite arithmetic series: n(a,tan) Sn where n is the number of elements in the series, az is the first element of the series, and an is the last...

The question is on the picture i posted. It ask  element store in the array in 8 above. If you need the array it will be:

Consider an array that stores the following sequence of integers:

     10, 15, 20, 25, 30

Extracted text: Consider the following equation for the sum of a finite arithmetic series: n(a,tan) Sn where n is the number of elements in the series, az is the first element of the series, and an is the last element of the series. Write a java method that returns the sum of the elements stored in the array in 8 above. The array must be passed to the method as an argument. Your solution should implement the equation for the sum Sn.