For any positive integer r, the sum of the first r positive integers equals r(r+1)/2 . If s and r are positive integers and s > r, what is the sum of all the integers between s and r, inclusive?	Choose the correct choice from the following
A) s(s+1)/2 + r(r+1)/2  B) s(s+1)/2 - r(r-1)/2  C) s(s+1)/2 - r(r+1)/2  D) s(s+1)/2 + r(r-1)/2  E) s(n+1)/2 - r(s-1)/2
The sum of all the integers between s and r,inclusiveis the sum of the first s positive integersminusthe sum of the first r-1 positive integers.   The sum of the first s positive integers is s(s+1)/2;   The sum of the first r-1 positive integers is (r-1)r/2;   Therefore the answer is s(s+1)/2 - (r-1)r/2.   Answer: s(s+1)/2 - r(r-1)/2.
<result>B</result>
For any positive integer r, the sum of the first r positive integers equals r(r+1)/2 . If s and r are positive integers and s > r, what is the sum of all the integers between s and r, inclusive?