Urgent :(please help me with these 2 questions

Trent wants to buy 2 packs of trading cards for 3 dollars each. the trading card packs that trent normally buys tend to come in packs of 6, 10, 12, or 15 cards. after selecting 2 packs, trent found that the first pack of cards cost 25 cents per card, and the second pack cost 30 cents per card. trent uses this information to write the equations below in order to compare c, the number of cards in each pack.

Identify the type of observational study described. a statistical analyst obtains data about ankle injuries by examining a hospital's records from the past 3 years. cross-sectional retrospective prospective

Can some one explain this i got sent this. is this a threat i’m scared