3. Give a summation that represents (a) the number of times the statement x += (n + i) is executed in the function below, and (b) the value returned by the function. Find the closed forms for both summations:

int foo(int n) { int x = 0; for (int i = 0; i < n; i++) for (int j = 0; j <= n; j++) x += (n + i); return x; }