Answer:
C. $300
Step-by-step explanation:
We have been given that Mr. Collins made 20 bird houses to sell at a carnival. He earns $15 for each bird house he sells.
To find the amount earned by Mr. Collin after selling all 20 bird houses, we need to multiply 20 by amount earned by selling each bird house.
Therefore, Mr. Collin will earn $300, if he sells all 20 bird houses.