I'm unsure about this question:

My working:

Then adding four to both sides:

Then I multiply both sides by three to get rid of the fractions, leaving me with

But according to the book, the final answer should have a positive eight rather than a negative eight. I'm not sure how to arrive at this answer (something to do with the first step in my working... is there a double negative on the right hand side?). Any help would be appreciated.