We define that K@J is the product of j number from k in increasing order for positive integers K, J. For example, 6@4=6*7*8*9. If A=2020and B=2120, what is the value W of the ratio A/B?	Choose the correct choice from the following answers
A) 1/2  B) 1/3  C) 2/3  D) 1/4  E) 1/5
W-&gt; A/B=20*21*……*39/21*22*….*39*40=20/40=1/2.   Therefore, the answer is 1/2.
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We define that K@J is the product of j number from k in increasing order for positive integers K, J. For example, 6@4=6*7*8*9. If A=2020and B=2120, what is the value W of the ratio A/B?