doubt on tutorial 01 week 3

[nibedita chakraborty]

Sir, 

In Q1 c) why are we adding 3x(1200) to 5000 rupees, does Vijay need to pay money for the equipment every 3 year ? 

And when it is said that the price for the equipment decrease every year why are we not considering the the decrease in price after the work life, that is the decrease in price in the 4th year in case of equipment A ?

Please answer these questions at your quickest.

Thank you

Your Sincerely

Nibedita