Can you solve this tricky maths equation problem by replacing ? mark with correct number ?

19834 -----: 187

15921 -----: 153

17561 -----: 137

13734 -----: ???

+1 vote

Can you solve this tricky maths equation problem by replacing ? mark with correct number ?

19834 -----: 187

15921 -----: 153

17561 -----: 137

13734 -----: ???

...