Answer:
1. 20 units
2. $600
Step-by-step explanation:
1.

MC = 4q
Price, P = $80
For maximizing profits,
Marginal cost = Price of the commodity
4q = 80
q = 20 units


= 200 + 800
= 1,000
2. Profit = Total revenue - Total cost
= (Price × Quantity) - TC
= (80 × 20) - $1,000
= $1,600 - $1,000
= $600
3. We know that the firm in the short run will be produce at a point where total revenue is greater than the total variable cost
Average variable cost = variable cost ÷ quantity

= 2Q
MC = 4Q
Here, MC is greater than AVC at any given point.
so in the short run firm will producing short run positive profit.