Question

An elevator is 180 feet above the first floor. each second it descends 12 feet

what integer is the change in the height of the elevator each second

Answer 1

`\bf \begin{array}{cll} \stackrel{passing}{seconds}&\stackrel{feet~above}{1st~floor}\\ \cline{1-2} 0&180\\ 1&180-12\\ &168\\ 2&168-12\\ &156\\ 3&156-12\\ &144\\ ...&... \end{array}\qquad \qquad \stackrel{\textit{change in the height integer}}{\underset{\textit{common difference}}{-12}}`

Answer 2

`-12`

Explanation:

Let x represent number of seconds.

We have been given that an elevator is 180 feet above the first floor. This means that elevation of elevator is positive 180.

We are also told that each second the elevator descends 12 feet. The elevation of elevation after x seconds would be
`-12x`.

The final elevation of elevation after x seconds would be
`180-12x`, where,
`-12` represents change in the height of the elevator each second.

Therefore,
`-12` is our required integer.