Can someone help me on this?

Aboat costs 19200 and decreases in value by 12% per year. how much will it cost in 5 years

Players on the school soccer team are selling candles to raise money for an upcoming trip. each player has 24 candles to sell. if a player sells 4 candles a profit of$30 is made. if he sells 12 candles a profit of $70 is made. determine an equation to model his situation?

How to simply and write the answer n a whole number