3a-c: You have $30,000. You want to invest your money into 5 companies by buying some shares. For each company, 1 share costs $1,000. In how many ways can you invest your money in each of the following cases:

3a. (6 points) You plan to invest all of your money .

3b. (4 points) You don't have to invest all of your money .

3c. (4 points) You plan to invest all your money, such that Company 1 has at least 5 shares of your investments.