120 men are used to build huge building for 30 days. How long will it take 80 men to do the same work?

120 men are used to build huge building for 30 days. How long will it take 80 men to do the same work?

Explanation

120 men can do work = 30 days

1 man can do this work = 120 x 30 = 3600 days

80 men can do this work = 3600/80 = 45 days