So in total 8+4 would be 12 spaces. Rmr when you calculate distance you can’t subtract a negative. A negative really means backwards not destroyed in terms of distance. So total is 12 spaces.
2/3 of 12 is 8. Think of it like this
2/3=x/12
You could do butterfly or you could realize 3x4=12
So 2x4=8 would be proportional to the ratio we are looking for.