Question

An elevator descends into a mine shaft at the rate of 6m/min. If the descent starts from 10m above the ground level, how long will it take to reach -350 m.

Answer 1

The distance elevator has to travel = 360 m 
rate(6) = distance traveled(360) / time taken(x)
6 = 360 / x
x= 60 minutes

Answer 2

The time taken to reach 350 m is 60 minutes or 1 hour.

Solution:

The rate of descend is 6m/min that means that, in every minute, the elevator descends by 6m.

The elevator starts at 10m above the ground means the starting point is above ground 10m to below 350m

The negative descend distance is -350m which means that it is 350m down therefore the total distance from above ground to below ground is    350 + 10 = 360m

Total distance of descend is 360m.

The speed of descend of the elevator is 6m/min.

Time taken to go the total 360m distance is $\bold{\frac{360}{6}=60}$ min or it can be also written as 1 hour.