This open response question gives students pictures where they need to set up equations from shapes given. They must understand combining like terms, solving equations with variables on both sides, and substitution in order to solve for the perimeter once they have set up their equation and solved.
There are two similar, but different questions in this download. I like to use one as a live scoring option and the other as the assessment. You could give both as the assessment if you wanted.
They are great questions to see if students know how to set up an equation, combine like terms, solve a multi-step equation then substitute their answer back in to see it if it reasonable and answer a question about their about work.