Adding/summing two arrays

Zip it :)

var a = new int[] {1,2,3 };
var b = new int[] {4,5,6 };
a.Zip(b, (x, y) => x + y)

You can use the Select method.

int[] a = new[] { 1, 2, 3 };
int[] b = new[] { 10, 20, 30 };

var c = a.Select ((x, index) => x + b[index]).ToArray();