2.5x-x=60
The solution is x=40.
X=40 fits the question.
∴ Storybook: 40+60= 100 (Ben)
A: There are 0/00 story books and 40 science and technology books.
2. Solution: If the younger brother is X years old, the older brother is 1.5x years old. Judging from the meaning of the question:
x+ 1.5x=30
The solution is x= 12.
X= 12 fits the question.
∴ Brother: 30- 12= 18 (years old)
A: My brother 18 years old, and my brother 12 years old.