Help in this as well

Acar dealership pays you 5% commission on your first $10,000 on car sales and 8% commission on the sale amount over $10,000 if you sold a $12,000 car how much is your commission

Iwill make brain if you me correctly fill this out needs due today pls and send it back to me (click the link and you will get it)

What number should be added to the expression x^2+3x+ in order to create a perfect square trinomial? 3/2 3 9/4 9