## Thinking Mathematically (6th Edition)

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