If a person's life span split by age 20 years since first birth is wairian. After that, as the working age to earn money for living. That some people have one and it worked! While some people study at a higher level and after that you had to write at the age of.
If the life span of a person under the age of 20 years, from birth to school age. After that is working to earn money for a living. Some graduate level, and then run it. While some people are studying at a higher level. And after that you just retired