Which of the followmg is an expression for "doubling a number n and dividing by 3"​

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.

Find two consexutive odd integers such that the sum of their square is 650

Out of 50 students surveyed, 16 have a dog. based on these results, predict how many of the 280 students in the school have a dog.