Question

An Elevator descends into a mine shaft at the rate of 5m/min. If the descend starts from 15m above the ground, how long will it take to reach 350m deep from the ground?

Answer 1

First of all, assuming that the "ground level" is 0; 

The lift is not starting from 0, so we also need to account for the extra 15 meters above the ground the lift is. 

The total distance the lift would cover in the downward direction: 15+350=365m

Now, you know that the lift covers 5 m/min

Therefore, 5x=365 (ignoring units because they can complicate things) 

x=365/5 
x=73 minutes 

Therefore, they would take 73 minutes to reach 350 m deep into the ground with a starting position 15 m above the ground. 

Hope I helped :)