Your demand curve for baseball tickets is as follows:

price per ticket Qd
$1 4
$2 3
$10 2
$20 1

YOu buy 2 tickets at $10 each. THe value yo you of the two tickets is what?

It say the answer is $30. I do not understand why you have to add 10 and 20. I thought it would just be greater than of equal to $20. Could someone please help me? Thanks