Aperson's heartbeat is 89 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.

In this question, you are asked the time but given the speed(89beat/min)  and the number of beats(3.1 x 10^9). Then the equation would be:

Time= number of beats/ speed
Time = 3.1 x 10^9 beats / (89 beats/min)= 3.483 x 10^7 minutes.

Then convert it to years, disregard of leap years it would be : 3.483 x 10^7 minutes / (60 minutes/hour) / (24 hour/day) / (365 day/year)= 66.26 years