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

That result from subduction of oceanic plates beneath lighter continental plates. most of the earth's volcanoes are located around the pacific ring of fire because that the location of most of the earth's subduction zones.