Known: Dad is 38 years old and Jiajia is 2 years old.

In a few years, my father will be five times as old as Jia Jia.

Suppose: x years later, dad is five times as old as Jia Jia.

38+x=(x+2)5 is replaced by 5 in brackets.

38+x=5x+ 10 shift project

38- 10=5x-x

28=4x

X=7 years

Answer; Seven years later, my father was five times as old as Jia Jia.