Explanation:
A Number between 1 and 10000 are formed
using digit 2 and 3 only once and digit 4 twice \(=\{2,3\),
\(4\}=3\)
Two 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 \(=\{2344,2434,2443,3244,3424\),
\(3442,4234,4324 \ldots\)..)
Rank of \(324=14\)
Rank of \(4324=3+7+12+9=31\)
\(\therefore \quad x-y=31-14=17\)