By Question it's given that the sum of two numbers is 15 . And we need to find out the numbers. So ,
Let us take :-
According to the Question :-
[tex]\sf\implies x + x +1=15\\\\\sf\implies 2x = 15-1\\\\\sf\implies 2x =14 \\\\\sf\implies x =14/2 \\\\\sf\implies\red{ x = 7 }[/tex]
Therefore :-
Hence the two numbers are 7 and 8.