Lencho had all his doubts on people working in the post office. The irony of the situation is that Lencho blames those who had tried to help him out . In real life also we come across such situations. Many a time you would have tried helping someone and he may get a wrong message. Lencho thinks that the post office people have taken the money. But the fact is that they only tried to help him by sending money . But, on the other hand, Lencho thinks they have stolen his money. He even calls them crooks. Thus ,there is an element of irony in this situation.
Assertion (A): The sum of the first fifteen terms of the AP $ 21, 18, 15, 12, \dots $ is zero.
Reason (R): The sum of the first $ n $ terms of an AP with first term $ a $ and common difference $ d $ is given by: $ S_n = \frac{n}{2} \left[ a + (n - 1) d \right]. $
Assertion (A): The sum of the first fifteen terms of the AP $21, 18, 15, 12, \dots$ is zero.
Reason (R): The sum of the first $n$ terms of an AP with first term $a$ and common difference $d$ is given by: $S_n = \frac{n}{2} \left[ a + (n - 1) d \right].$