Chapter 5 - Number Theory and the Real Number System - 5.2 The Integers; Order of Operations - Exercise Set 5.2 - Page 270: 125

$1$ year

A person who frequently feels stretched will shrink his/her lifespan by 5 years. The number that represents this is $-5$. A person who has less than 12 years of education shrinks his/her lifespan by 6 years. The number that represents this is $-6$. Thus, the difference between the lifespan of the two is: $=-5 - (-6) = -5+6=1$ year