Can someone please help I'm really confused about these 2 problems( pictures attached) no links, please.

The table represents a function f(x). what is f(3)? a.-9 b.-1 c.1 d.9

If you could answer these your a life saver

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )