A brokerage house offers three investment portfolio options. Portfolio I consists of 2 blocks of common stock and 1 municipal bond. Portfolio II consists of 4 blocks of common stock, 2 municipal bonds, and 3 blocks of preferred stock. Portfolio III consists of 7 blocks of common stock, 3 municipal bonds, and 3 blocks of preferred stock. A customer requests a total of 21 blocks of common stock, 10 municipal bonds, and 9 blocks of preferred stock. How many units of each investment portfolio should be offered to the customer ?

1. How many units of portfolio I should be offered to the customer?

2. How many units of portfolio II should be offered to the customer?

3. How many units of portfolio III should be offered to the customer?

4. How many total blocks of common stock, preferred stock, and municipal bonds will the customer hold across all portfolios?