3. (3 pts.) On the first day of opening a new restaurant, the owner found that he made a $500 profit. Suppose P(t) is the amount of profit he makes t days after he opened his restaurant. Write a formula for each of the following. (a) The profit increased by $200 per day. P= (b) The profit increased by 10% each day. P= (c) The profit decreased at a continuous rate of 5% each day. P=