20 builders can excavate a building in 50 days. After 10 days, 20 more builders join them. What is the time taken to finish the remaining work?
1
28 days
2
10 days
3
20 days
4
22 days
20 builders can excavate a building in 50 days. After 10 days, 20 more builders join them. What is the time taken to finish the remaining work?