Math problems in the fifth and sixth grades of primary school: books in the school library ...
Solution: Set up X original books and get them according to the meaning of the questions.
40%X+ 120=48%(X+ 120)
Solve the equation:
0.4X+ 120 = 0.48(X+ 120)
X+300= 1.2(X+ 120)
X+300= 1.2X+ 144
300- 144= 1.2X-X
0.2X= 156
X =780
The school has 780+ 120=900 books.