3. Mr. Mele has been buying many plaid shirts recently. The linear equation used to model the amount of money in his bank account (y) based on the number of shirts bought, x, is y=-45x + 700. What is the rate of change and what does it represent? (a) The rate of change is $700 and it represents the initial amount in his account.

(b) The rate of change is - 45 and it represents the cost of each shirt.

(c) The rate of change is - 45 and it represents the amount his bank account goes down per • shirt he buys.

(d) The rate of change is - 45 and it represents the amount of money in his bank account