Solution:
Number between 1 and 10000 are formed using digit 2 and 3 only one and digit 4 twice one-digit ={2,3,4}=3
Two digit ={23,24,32,34,42,43,44}=7
Three digit number ={234,243,244,324,342,344
423,432,424,434,442,443}=12
Four digit number ={2344,2434,2443,3244,3424,,
3442,4234,4324...}
Rank of 324=14 Rank of 4324=3+7+12+9=31
∴ x−y=31−14=17
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