Which order does this go in?

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.

You are at a restaurant and owe $38 for your meal. you want to leave a 20% tip. how much will your tip be?

The suare root of 9x plus 7 plus the square rot of 2x equall to 7