Respuesta :

Well we can find out how many used books there are by subtracting 8 from 13 which gives us 5. Then we put that in a ratio for all to used it would be 13:5 or 13/5
Used to new would be 5:8 or 5/8
Tuniss
13-8= 5 so 8 new, 5 used

A. all to used 13:5

B. used to new 5:8