If X is the sum of first 20 positive even integers and Y is the sum of first 20 positive odd integers, what is the value of x-y?\nPlease try to explain your answers\nOptions:\n(A) 0\n(B) 20\n(C) 50\n(D) 75\n(E) 100 Stream of consciousness first, then make a decision:
User
First even minus first odd = 2-1 = 1;\nThe sum of first 2 even integers minus the sum of first 2 odd integers = (2+4)-(1+3) = 2;\nThe sum of first 3 even integers minus the sum of first 3 odd integers = (2+4+6)-(1+3+5) = 3;\nWe can see the patterns here, so the sum of first 20 positive even integers minus the sum of first 20 positive odd integers will be 20.
Thus, the answer is (B).
Assistant