What is the sum of a geometric series of 12 terms that begins with 10 and has a common ratio of 2

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.

Combine like terms to make a simpler expression 3z+z

Find the value of x. give reasons to justify your solutions! l, m ∈ kn