If two integers x, y (x>y) are selected from -10 to 10 (inclusive), how many possible cases are there?
Choose the correct choice from the following answers: A) 150 B) 180 C) 190 D) 210 E) 240
If two integers x, y (x&gt;y) are selected from -10 to 9 (inclusive), how many possible cases are there?   A. 150   B. 180   C. 190   D. 210   E. 240   --&gt; 21C2=21*20/2= 
<gadget id="calculator">21*20/2</gadget>
<output>210</output>
210. Therefore, the answer is 210
<result>D</result>
If two integers x, y (x>y) are selected from -10 to 10 (inclusive), how many possible cases are there?