To evaluate and simplify 2/3a - 1/8b + 1/6a, let's combine like terms:
First, add the a terms together:
2/3a + 1/6a = 4/6a + 1/6a = 5/6a
Now, add the b term:
5/6a - 1/8b
This expression cannot be simplified further without additional context or values for a and b. So, the simplified expression is 5/6a - 1/8b.