How can you be certain that the angles you have created form a square inside the
circle?

Step-by-step explanation:

Make sure that the angles are the same length, also make sure that the diameter of the circle is not smaller than that of the square to find diameter of a circle multiply the radius by 2, to find the radius use this formula  

r=C  over 2π

Question 1.  The answer is $1900.  Her weekly pay is $95.  $475-$95=$380
$1900 * 20% = $380.
Question 2.  Decrease by 14.3%   823*.143=118 students.  823-705=118
Question 3.  56%   99.99-64.25=35.74 difference in price.    64.25*.56=35.98.  The other percentages are too low or too high