JAVA PROGRAMING- Need Help with this asap!

(20) 1. Develop a method sum that given an integer n, return the value of the following series.

S = +

(20) 2. Develop a method called count that given two integers k1 and k2 returns the number of integers between k1 and k2 that are divisible by either 3 or 5 but not both, return the count.