mathematics

First, we need to find how many cards Jason purchased. 12 packages * 35 cards= 420 cards

 

if 1/7 of the cards are pitchers, then 6/7 feature batters.

 

6/7*420=360

so  

360 cards featured batters.

12 packages * 35 cards = 420 total cards.

1/7 of 420 = 420 * 1/7 = 60

if 60 cards were pitchers, then 420-60 = 360 cards were batters