I think it is B -2 < x < 2
500=4πr^2. first divide 500 from four which will equal 125, then divide 125 with π and it will equal 39.788 . finally √39.788. the answer will be r=6.3 or 6
check the picture below.
you can check in your calculator, make sure your calculator is in Degree mode.
AT&T: $0.15 per minute
Sprint: $0.12 per minute
Sprint is the better deal.
12% = 12/100 = 0,12
0,12 x x = 9
x = 9/0.12
x = 75
9 is 12% of 75