72a^7/-9 as a monomial

The perimeter of a movie screen is 54 meters. the screen is 18 meters wide. how tall is it?

Im gonna fail 7th grade selective breeding 1. creates offspring which are genetically identical to the parent 2. is the process of breeding only organisms with desirable traits 3. involves the removal of the nucleus of a cell 4. combines traits from organisms of different species

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?