The words w1, w2, w3 and w4 possess the following features:ׁ
1. All are 3-letter English words.
2. Only one of them has 2 distinct letters.
3. w1_ie S. was a famous bandleader.
4. w2 is a stage name of the American rapper-songstress J. Jeffers.
5. w3_ford is a name of a location both in Somerset, U.K. and in Manitoba.
6."Get thee to a w4_ery" is a known quotation.
Now solve the easy alphametics and find the digit not appearing in it:
w2+w3=w1
w2-w3=w4