Step-by-step explanation:
Let b be the book
1/3b is the amount he finished on the first day
1/4b is the amount he finished on the second day
b - (1/3b + 1/4b) is how much he has left
b- (4/12b + 3/12b) make the denominators the same
b- 7/12b add the fractions
5/12b The answer
John has 5/12 of the book to finish
I am sorry if this isn't the answer you wanted
But I hope this helps in someway!!!!