Okay so we know that 20% of books are mysterious, now we need to know what percentage of books are adventurous. This can be done through: (18/85)×100= 21% (as a whole number, to 1 d.p. it would be 21.2%)
So if 20% are mysterious and 21% are adventurous, 100-20-21= 59% must be fantasy
The fraction is 59/100 so the ratio is 59 : 100, which cannot be simplified further as 59 is a prime
