We are trying to solve 27-2/3. Firstly, using the index rule axy= (ax)y, this can be rewritten as (271/3)-2. Lets tackle the value inside the bracket first: 271/3 means the cube root of 27, and so is 3 (as 33 = 27). Therefore we have 3-2. Any value to the power of a negative becomes one over that value. As a result, we have 1/(32) = 1/9