I'm struggling in these questions. Please help me to explain. Thank you so much!

1. A Dell computer is a substitute for a HP* computer. What happens to the demand for HP computers and the quantity demanded of Dell computers as the price of a Dell falls?

2. Describe how each of the following will affect the supply of personal computers:

• A rise in wage rates;
• An increase in the number of sellers of computer.

3. Describe how each of the following will affect the supply of personal computers:

• A tax placed on production of computers;
• A subsidy placed on the production of computers.

4. Many of the proponents of price ceilings argue that government-mandated maximum prices simply reduce producers' profits and do not affect the quantity supplied of a good on the market. What must the supply curve look like before a price ceiling does not affect quantity supplied?