How do i do #3? i'm confused because i did it and i got 28 i did it twice but my teacher said that's not right answer

You were so close! The correct answer is -33. You did all of your steps right in the beginning, but -30 - 3 is not 28, it's -33. If you have to add or subtract and you have 2 negative signs, then you keep that sign and add the numbers together. I remember this by singing a song to myself to the tune of Row Row Row Your Boat to help me. My 7th grade math teacher came up with it for our class. 

Step-by-step explanation: To find the area of the circle,

start with the formula for the area of a circle, which is .

Notice that our circle has a radius of 8 units.

So plugging into the formula, we have (π)(8 units)².

Now, (8 units)² is equal to 8 units × 8 units or 64 units².

So we have 64π units² which is an exact answer.