Aperson's heartbeat is 71 beats per minute. if his/her heart beats 3.1e9 times in a lifetime, how long (in whole years) does the person live? disregard leap years.

First step: identify how many heart beats in a year.

To determine the heart beats in a year multiply the heart  beats in a minute with years.  

Thus, heart beats in a year comes out to be =

= heart beats in a year

Heart beats in a life time.

Thus, number of years he lives is calculated by the division of  heart beats in a year and heart beats in a life time.

Number of years he lives =

=

=

= years

Thus, number of years he lives is years