If 6 men can complete a task in 10 days, how long will it take for 15 men to complete the same task?

Question: If 6 men can complete a task in 10 days, how long will it take for 15 men to complete the same task?

Solution:
Formula used: M1 × T1 = M2 × T2
Where M1 and M2 is men and T1 and T2 is time

∴ 6 × 10 = 15 × t
⇒ t = 60/15
∴ t = 4 days