Cómo resolver por método de sustitución​

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.

Precalculus question, image attached.

(03.03 mc) choose the graph below that correctly represents the equation 2x + 4y = 24. (5 points) select one: a. line through the points 0 comma 6 and 12 comma 0 b. line through the points 0 comma negative 6 and 12 comma 0 c. line through the points 0 comma negative 12 and 6 comma 0 d. line through the points 0 comma 12 and 6 comma 0