(a) Using \"stars and bars\

(a) Using "stars and bars", show that the number of ways to select an unordered group of seven numbers using numbers from 1 through 19 (inclusive) with repetition allowed is equal to 480, 700. (b) What if the sum of the group of chosen numbers must be odd? That is, how many ways are there to select an unordered group of seven numbers from 1 through 19, with repetition, so that the sum of the numbers is odd? Briefly explain your answer.