We are given this chart:

Hello, I was given this problem on a practice test and need some help understanding the answer. We are given this chart:

Price | Quantity Supplied | Quantity Demanded

70 | 400 | 100

60 | 350 | 200

50 | 300 | 300

40 | 250 | 400

30 | 200 | 500

20 | 250 | 600

The question is:

 If the world price of steel is $20, and the US enacts an import quota of 150 units, with no associated licensing fee, what will the price of steel be equal to in the US market after the quota takes affect?

A)  $20

B)  $30

The answer is the one in red ($40). Can you explain how to come up with this? Thanks.

Also - this is a business, govt., and society class, but that wasn't a topic option so I picked macro because that was the next most relevant subject.

Thanks.