so we can take X as the n.o of pages of the entire book so 1x/5 +40= 7x/10 pls remember the total n.o of each book is X therefore 40=7x/10-1x/5 to solve this u need to make the denominator's the same 40=7x/10-2x/10 40=5x/10 40*10=5x 400=5x 400/5=X 80=x