If 16 men can do a job in 20 days, then 32 men can do the same job in _____ days?

If 16 men can do a job in 20 days, then 32 men can do the same job in _____ days?

Explanation
16 men can do a job in 20 days
Total Work=16*20=320
Let 32 men do the same job in X days
32x=320
x=320/32
x=10