PLEASE HELP ME I NEED HELP DUE SOON

Average acceleration: i have no idea how to do this.

For the following geometric sequence, find the recursive formula. {-80, 20, -5, } i need : ')

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax