From CPM Mathematics:
Assuming the students have just completed the lesson on the Substitution Method, I’ll begin the Elimination Lesson by having the students work out the following system:
2x+3y=-2
5x-3y=16
A minute in, they will likely become annoyed due to the fractions created by getting a variable alone. Stop them midway through the problem and ask “What’s annoying about this problem?” to which they’ll say the fractions. I’ll then ask them if anyone sees a different, “better” way to do this problem. Begin Elimination method.