The function f(x) is graphed on the coordinate plane. what is f(-4)?

With both problems. a. s.a. p directions on photo ^

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! )

Each unit cost 14p, how much would 942 units cost?