Austin remove three fish from his pond each day for 15 days what was the total change in the number of fish in the pond

Which recursive formula can be used to determine the total amount of money earned in any year based on the amount earned in the previous year? f(n+1)=f(n)+5

Marla bought a book for $12.95, a binder for $3.49, and a backpack for $44.99. the sales tax rate is 6%. find the amount of tax and the total she paid for these items

Is this a polynomial function? i need to know asap