Suppose you draw a single card, what number do you expect on it?? Let's calculate that first.
it would be, 1/80 * 1 + 1/80 * 2 + 1/80 *3 +.............................. 1/80 * 80
= 1/80 * (80 *81)/2
=40.5
So if you select one card out of 80 cards expected number on it is 40.5
For 30 cards, the Expected value will be, 40.5 *30 =1215