Jaco and Wang Han have a total of 70 math extracurricular books. After Jaco gave Wang Han five books, they had as many books as they did.

Solution: Suppose Zhang Bo has X math extracurricular books and Wang Han has 70-x math extracurricular books.

x-5=70-x+5

x-5=75-x

x+x=75+5

2x=80

x = 80 \2

x=40

Wang Han has books =70-x=70-40=30.

A: It turns out that Zhang Bo has 40 math extracurricular books and Wang Han has 30 math extracurricular books.