Suppose y varies directly with x and y = -9 when x = 3. what is y when x is 18

Can someone me with these two circle theorem questions asap?

Do you mind if you guys me with this question i’m on number 8

The salesperson earns a 5% commission on the first $5,000 she has in sales. the salesperson earns a 7.5% commission on the amount of her sales that are greater than $5,000. this month the sales person had $8,000 in sales. what amount of commission, in dollars, did she earn?