Answer: [tex]y+8[/tex]
Step-by-step explanation:
Given : The present age of John is denoted as 'y'.
Then, the mathematical expression represents John's age in eight years will be :-
[tex]y+8[/tex] [We add 8 to y]
Therefore , the expression represents John's age in eight years, when y represents his present age is [tex]y+8[/tex].