An asset with a first cost of $100,000 is depreciated over 5-year period. It is expected to have a $10,000 salvage value at the end of 5 years. Using the straight-line method, what is the book value at the end of year 2?

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.