Question

find first three natural numbers such that the sum of the first two numbers is 15 more than third

Answer 1

Let the numbers be n, n+1 , n+2. (since its mentioned first three which means consecutive)
Given,
n + n+1 = 15 + n+2
2n + 1 = 17 + n
n = 16
Hence the numbers are 16, 17, 18

Answer 2

Answer

Let numbers = x, x+1, x+2

x + x + 1 = x + 2 + 15

=> 2x = 17 + x - 1

=> x = 16

Numbers = 16, 17, 18