Remark
Many calculators have a key that will do this in one step. Mine is one of them. So let's start with the answer and then we'll do it the long way.
9C3 = 84. You put it into your calculator as 9 2nF nCr 3 =
Solution

3*4*7 = 84 which is what you set out to show.
You are looking for three consecutive integers whose sum is 93. First, divide 93 by 3 and get 31. Go one above 31 and one below. You get 30, 31 and 32 which sum to 93.
is the answer.
This is because the slop is found by the difference of ys over the difference of xs.
Answer:
Tax=$0.91
Step-by-step explanation:
Tax=$12.99(.07)=$0.9093
Tax=$0.91