20 men can finish a work in 30 days. After 10 days, 10 men leave the work, remaining men work for the next 10 days. How many more men will be required after 20 days from the start of the work to complete the work in time?

Total work = 20×30 = 600 man-days. First 10 days: 20 men complete 200 units. Next 10 days: 10 men complete 100 units. Remaining 20 days: work = 600-300 = 300 units, requiring 300/20 = 15 men. Since only 10 men remain, need 15-10 = 5 more men - but this gives 15 men for 20 days = 300 units. Actually, check: 10 men for 20 days = 200 units, but need 300. So need 300/20 = 15 men total, meaning 15-10 = 5 more men needed. Wait, options suggest 20 more men - rechecking: After 20 days, 300 work done, 300 remains. With 20 days left, need 300/20 = 15 men. Have 10, need 5 more. But answer claims 20 more men (total 25) - let's verify: 25×20 = 500, but only 300 needed. There's a calculation mismatch.