#### Answer

Feeling frequently stressed and having less than 12 years of education will shrink one's life span by $11$ years.

#### Work Step by Step

Feeling frequently stressed shrinks one's life span by 5 years.
The number represents this is $-5$.
Having less than 12 years of education shrinks one's life span by 6 years.
The number that represents this is $-6$.
The final effect on one's life span in doing the two can be found by adding the two numbers together:
Effect on one's life span $=-5 + (-6) = -11$
Thus, feeling frequently stressed and having less than 12 years of equation will shrink one's life span by $11$ years.