DS acquired a building for Rs. ` 15 lakh in June, 2016 in addition to cost of land beneath the building of ` 3 lakh. It was used for personal purposes until he commenced business in June, 2018 and since then it was used for business purposes. The amount of depreciation eligible in his case for the assessment year 2019-20 would be -

A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. 
An 'information system' means a discrete set of information resources organized for the collection, processing, maintenance, use, sharing, dissemination, or disposition of information.

Engineering economics, previously known as engineering economy, is a subset of economics concerned with the use and "...application of economic principles" in the analysis of engineering decisions.