The official currency of Japan is the Yen (¥). It is one of the most widely traded currencies in the world.
Euro: Currency of the European Union countries.
Yuan: Currency of China.
Dollar: Used by several countries, including the United States.
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]. $