एक पुस्तक विक्रेता ने ₹ x प्रति पुस्तक की दर से भूगोल की ‘a’ पुस्तकें बेचीं, ₹ (x + 2) प्रति पुस्तक की दर से इतिहास की ‘a + 2’ पुस्तकें बेचीं तथा ₹ (x − 2) प्रति पुस्तक की दर से गणित की ‘a − 2’ पुस्तकें बेचीं। उसकी कुल बिक्री (₹ में) कितनी है?
Read this question in English
A bookseller sold ‘a’ number of Geography textbooks at the rate of ₹x per book, ‘a + 2’ number of History textbooks at the rate of ₹(x + 2) per book and ‘a − 2’ number of Mathematics textbooks at the rate of ₹(x − 2) per book. What is his total sale in ₹?
(a) 3x + 3a · (b) 3ax + 8 · (c) 9ax · (d) x³a³
उत्तर और व्याख्या · explanation in English
Answer: (b) 3ax + 8
Total sale = ax + (a + 2)(x + 2) + (a − 2)(x − 2). The terms 2a + 2x and −2a − 2x cancel, leaving 3ax + 8.
- Geography: a × x = ax.
- History: (a + 2)(x + 2) = ax + 2a + 2x + 4.
- Mathematics: (a − 2)(x − 2) = ax − 2a − 2x + 4.
- Sum: 3ax + 8.
- Check with a = 3, x = 5: 15 + 5 × 7 + 1 × 3 = 53, and 3 × 3 × 5 + 8 = 53.
Remember · Check algebraic options by putting small numbers into both the question and each option.
Question and answer: UPSC's official GS Paper II (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·