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 two 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

69, 87 = 39

93, 95 = 47

52, 64 = ?