Let first number be x.
According to the question second number is x + 1 and the third is x + 2
Sum of first and second numbers = (x) + (x + 1).
According to question:
⇒ (x) + (x + 1) = 15 + (x + 2)
⇒ 2x + 1 = 17 + x
Transposing x to LHS and 1 to RHS, we get
⇒2x – x = 17 – 1
⇒ x = 16
So, first number = x = 16,
Second number = x + 1 = 16 + 1 = 17
And third number = x + 2 = 16 + 2 = 18
Thus, the required consecutive natural numbers are 16, 17 and 18.