Help lol solve for x

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.

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Find the area of just the wood portion of the frame. this is called a composite figure. you will need to use your values from problem #2need all exepct 4 answerd if you can