Your students will beg for more circuits after they work just one. This circuit starts easy with a two-step equation, but builds from there and includes distributing, combining like terms, variable on both sides, some decimals and fractions as coefficients, and even a few literal equations at the end.
If you want a slightly easier circuit on solving equations, check out this one in my store: https://www.teacherspayteachers.com/Product/Circuit-Training-Solving-Linear-Equations-middle-school-2482742
or check out Nicole Lang's Mathematical Circuit Training (link: https://www.teacherspayteachers.com/Store/Nicole-Langs-Mathematical-Circuit-Training) ! She has lots of great circuits!
To advance in the circuit, students must find their answer among the choices, and the problem associated with that answer choice becomes the next one for them to work. I have been teaching for 25 years so I know what students' common errors and misconceptions are so I weave them into the circuit. Great for guided practice, independent practice, cooperative learning, differentiated instruction -- you name it! Can be made into task cards or a scavenger hunt too.
There is no answer key included in my circuits, because the answers are within the circuit. The teacher should work the circuit before the students do, but that is the only prep needed for that day!