Answer:
33
Step-by-step explanation:
let g be Gabrielle age
m be mikhail age.
So according to this problem,
[tex]g + m = 81[/tex]
[tex]m + 15 = g[/tex]
Subsitue m+15 for g.
[tex](m + 15) + m = 81[/tex]
[tex]2m + 15 = 81[/tex]
[tex]2m = 66[/tex]
[tex]m = 33[/tex]
So mikhail age is 33.