Few men were sitting in a row facing north in a row.
Sunil is 16th to the left of Ram, who is 18th from the right. Jack is 11th from left and is also 4th to the right of Sunil. How many men were sitting in a row.

From the first sentence we can say that there are 15 people between Ram and Sunil and Ram has 17 peole to his right.

Jack is 4th to right pf Sunil, so he must have 3 people between him and Sunil. Since there are 15 people between Sunil and Ram, we can say that there will be 15 - 4 = 11 people between Jack and Ram. 

Jack is 11th from left and he also has Sunil to his left. Jack will have 10 people to his left and Sunil is 4th to his left , This must mean that Sunil will have 10 - 4 = 6 people to his left. 

Hence we can say that there are 6 + 1 +3+1 +11 +1 + 17 = 40 people in the row