The given expression is:
[tex]8t^3+8y+7t^3+6y+9t^2[/tex]The like terms in the expression are terms having the same variable and the same power to the variable.
Now, combining the like terms,
[tex](8t^3+7t^3)+9t^2+(8y+6y)[/tex]Now, simplify by adding the like terms.
[tex]15t^3+9t^2+14y[/tex]So, the simplified expression is,
[tex]15t^3+9t^2+14y[/tex]