If $7 \oplus 9 \oplus 10 = 8$ , $9 \oplus 11 \oplus 30 = 5$ , $11 \oplus 17 \oplus 21 = 13$ , what is the value of $23 \oplus 4 \oplus 15$ ?

Kepler. Discussing PYQs. Q.no. 24

If 7⊕9⊕10=87 \oplus 9 \oplus 10 = 87⊕9⊕10=8 , 9⊕11⊕30=59 \oplus 11 \oplus 30 = 59⊕11⊕30=5 , 11⊕17⊕21=1311 \oplus 17 \oplus 21 = 1311⊕17⊕21=13 , what is the value of 23⊕4⊕1523 \oplus 4 \oplus 1523⊕4⊕15 ?