What is 2.80 increased by 20 percent

Iwill make brain if you me correctly fill this out needs due today pls and send it back to me (click the link and you will get it)

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

How many different three-digit numbers can be formed using the digits 1 comma 2 comma 9 comma 6 comma 4 comma 3 comma and 8 without repetition? for example, 664 is not allowed.