1. Consider a monopolist facing the following market demand function:

$$Q = 120 - 2P$$

where $Q$ denotes quantity demanded and $P$ denotes price.

The firm's total cost function is given by:

$$TC = 20Q + 100$$

Answer the following questions:

(a) Derive the marginal revenue (MR) function and the marginal cost (MC) function. \((5\%)\)