The sum of 15% of a positive number and 20% of the same number is 126. What is one-third of that number

Let the positive number be N.
According to the question
N x (15+ 20)% = 126
⇒ N x 35 = 126 x 100
∴ N = 12600/35 = 360
So, one-third of the number = 360/3 = 120