Help! I don't understand rate of change??

What are the coordinates of the hole in the graph of the function f(x) ? f(x)=x2−9x−3 enter your answer in the boxes.

Ifurniture stores having a weekend sale and is offering 20% discount on patio chairs and table the sales tax on furniture is 6.25 using function composition how can you represent the total amount a that you would need to pay for this furniture that cost x dollars

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