The sum of 30 times (1-3)^(n-1) from n=1 to infinity

Ineed to learn how to solve this problem

You purchased 8 pounds 10 ounces of candy from a candy shop. you want to split it equally among 3 classrooms at a local school.

The input to the function is x and the output is y. write the function such that x can be a vector (use element-by-element operations). a) use the function to calculate y(-1.5) and y(5). b) use the function to make a plot of the function y(x) for -2 ≤ x ≤ 6.