This is what I would call a Level I Elimination activity. The first 4 problems can easily be eliminated, and the rest, you only have to multiply one of the equations to eliminate a variable.
Riddles are a great way to make a boring worksheet fun. However, I found students knew the answer to the riddle and just chose the answers to fill in the letters without doing any of the math. This way, students have to create the riddle before they can answer it.
* Perfect for centers, homework or independent/group practice
* Engaging activity for students to practice
* Answer Key included