#### Answer

Taking 81 mg of aspirin per day and eating red meat more than twice a week will neither stretch nor shrink one's life span.

#### Work Step by Step

Eating red meat more than twice a week shrinks one's life span by 5 years.
The number represents this is $-5$.
Taking 81 mg of aspirin per day stretches one's life span by 5 years.
The number that represents this is $5$.
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 $=-5 + 5 = 0$
Thus, taking 81 mg of aspirin per day and eating red meat more than twice a week will neither stretch nor shrink one's life span.