A certain numbe of men can finish a piece of work in 100days.If have were 10 men less it would take to days more for the work to be finished.How many men were there originally?

Explanation:

Originally let there be x men.

Less men, More days (Indirect Proportion)

Therefore, (x-10) : x :: 100 :110

=> (x – 10) * 110 = x * 100 => x= 110