পিতা পুত্রের বর্তমান বয়সের পার্থক্য ১৫ বছর । ৩০ বছর পর তাদের  বয়সের পার্থক্য কত হবে?
To solve this problem, let's analyze it step-by-step:

Step-1: The age difference between father and son is 15 years now. Let, age of the father is X and the age of the son is Y now. So, X-Y = 15

Step-2: After 30 years father’s age is X+30 and son’s age is Y+30. So, difference of their ages is (X+30)-(Y+30) = X+30-Y-30 = X –Y = 15 (from step-1)

Step-3: So, age difference of father and son after 30 years will be 15 years.
                  
#Answer: 15 years