How do i write a word problem comparing fractions?

Just put all the fractoins into word form :)

Bob read 1/4 of the book on saturday
he read 1/3 of the book on sunday
how much more of the book does he have to read?

solution
1/4+1/3+?=1
3/12+4/12+?=12/12
7/12+?=12/12
?=5/12
has 5/12 book left to read