The logic here is,
15 - 6 = 9
36−15=21
75−36=39
Now see the difference of the differences
21 - 9 = 12
39−21=18
It is increasing by 6 so the next difference will be 24
so, 39 + 24 = 63
The next term will be,
75 + 63 = 138
The correct option is (B): 138
Identify the number that will replace the question mark in the second equation based on the relationship represented in the first equation.