At a new job selling high-end clothing to women, you earn $6 \%$ commission on all sales you make after the first $\$ 500$. Your pay can be represented by $p=0.06(s-500)$ dollars, where $s$ is the amount of sales you make in dollars.
a. How much total pay will you earn from $\$ 2000$ in sales?
b. How much total pay will you earn from $\$ 5000$ in sales?
c. If you need at least $\$ 450$ per week to pay your bills, what sales do you have to make per week?