In each of the given number-clusters, the number on the right side of = (the equal to sign) is calculated by performing certain mathematical operations on the three numbers on the left of = (the equal to sign). All three number-clusters follow the same pattern. Select the number from among the given options that can replace the question mark (?) in the third number-cluster.
36, 58, 21 = 23
41, 39, 20 = 20
39, 52, 34 = ?
1
17
2
30
3
25
4
15