Simplify the expression: 3a + 7/8 b + 5/6 c

The expression provided is a sum of three terms involving variables $a$, $b$, and $c$.

The terms $3a$, $\frac{7}{8}b$, and $\frac{5}{6}c$ are all unlike terms because they involve different variables ($a$, $b$, and $c$). Unlike terms cannot be combined through addition or subtraction.

Since there are no like terms to combine and no further operations are indicated (such as setting the expression equal to something or providing values for $a, b, c$), the expression is already in its simplest form.