This is basically how they got the correct answer. 
First they used the area formula:

So for you that would be:

Which equals
301.7
Since there's a hole in the circle we do the area of a square which is base times height. 
Which is 3 x 3 = 9 for your problem
Then we subtract
301.7 - 9 = 292.7 ! 
Which is almost exactly 292.57 since there is a margin