Question

an elevator descends into a mine shaft at the rate of 10 metres per min if it descends starts from 12m above the ground level how long will it take to reach -500mtrs

Answer 1

500+12=512 is total distance 
since +12 to 0 is 12 and 0 to -500 is 500.

speed=10m/minute

10/1=512/___
10/1=512/51.2

51.2 minute is the ans.

Ans:51.2 minutes or 51minutes 12seconds

Answer 2

Starting point = +12m
ending point = -500 m
total distance = 12 - (-500) = 12 + 500= 512m

speed = 10 meter per minute

time = distance / speed
       = 512 / 10
       = 51.2 minute
       = 51 minute 12 second