You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

[Q]: Question: For any positive integer Y, the sum of the first Y positive integers equals Y(Y+1)/2 . If X and Y are positive integers and X > Y, what is the sum of all the integers between X and Y, inclusive?

Option A: X(X+1

Option B: X(X+1

Option C: X(X+1

Option D: X(X+1

Option E: X(Y+1
[A]: Option B

[Q]: Question: Three number are in the ratio 5:6:7. The sum of its largest and smallest numbers equals the sum of the third number and 48. Find the third number?

Option A: 87

Option B: 57

Option C: 48

Option D: 26

Option E: 28
[A]: Option C

[Q]: Question: Felix earned 50% more per month than Oscar. If Felix's salary is decreased 10% and Oscar's salary is increased by 10%, then Felix would be earning what percent more than Oscar?

Option A: 25%

Option B: 9.09%

Option C: 14%

Option D: 22.73%

Option E: It cannot be determined from the information given.
[A]:
Option D