Acompact disk (cd) has a diameter of 12 cm. the hole in the middle has a diameter of 1.5 cm.
what is the area area of the disk?

The area of a circle is pie r squared. so you are going to want to find the area of both circles and then because the middle of the disk is empty space, you will subtract the middle area from the bigger area. 
first, find the radius. The radius is the diameter divided by 2. So it is 6cm for the big circle. Then in the area equation the radius is squared so you get 36cm and then to get the final area you multiply by pie. (i don't have a calculator with me sorry). 
next, you want to find the area of the smaller circle. Do the same process and use the equation. You should get 0.5625 times pie.
Then the last step is taking 36cm times pie divided by 0.5625 cm times pie and you get your answer

Y=-2x-6 is the answer