The three sides of a triangle are 15, 25 and x units. Which one of the following is correct?

In a triangle
Sum of two sides is always greater than 3rd side
i.e., x < 25 + 15 = 40 .....(i)
Difference of two sides is always less than 3rd side
i.e., 25 - 15 = 10 < x ...(ii)
From Eqs. (i) and (ii) , we get
10 < x < 40