A.)Rachel should have 6 second class tramps. Because if you do the equation 6+6+6 you get 18 (the number of first class stamps she has)
2.)Add 6 to 18 to get your answer :)
The equation of a circle:

(h, k) - a coordinates of the center
r - a radius

Answer:
the center: (3, -2)
the radius: 3
The square root of 125 is in between 11 and 12. It is 11.1803.
First you want to times 123.99 * 0.08
now round what you get (9.9192) to (9.92)
add that to 123.99 and then add 19.99 (Shipping)
The answer is $153.90