A takes 10 days less than the time taken by B to finish a piece of work. If both A & B can do it in 12 days, then the time taken by B alone to finish the work is- एक कार्य पूरा करने में A को B की तुलना में 10 दिन कम लगते हैं। यदि A तथा B दोनों मिलकर वह कार्य 12 दिनों में पूरा कर सकते हों तो अकेले B को वह कार्य पूरा करने में कितना समय लगेगा?

Let B take x days alone. Then A takes (x-10) days alone. Their combined rate: 1/(x-10) + 1/x = 1/12. Solving: (x + x - 10)/[x(x-10)] = 1/12, so (2x-10)×12 = x(x-10). This gives 24x - 120 = x² - 10x, or x² - 34x + 120 = 0. Solving: x = [34 ± √(1156 - 480)]/2 = [34 ± √676]/2 = [34 ± 26]/2. So x = 30 or x = 4. Since A takes (x-10) days, x cannot be 4. Thus x = 30 days.