You probably know that the GMAT rewards you for recognizing patterns. One type of pattern to watch for on GMAT Quant questions is the appearance of the same combination of variables in two different equations. When you see this type of pattern, you can substitute for an entire combination of variables at once. This can help you to simplify the math more quickly than if you just substitute for a single variable. Please contact me if you would like me to create a video explaining how to recognize and eliminate combinations of variables using substitution.

Here are lists of questions that you can use to practice eliminating combinations of variables using substitution, so that you can answer questions more efficiently and increase your GMAT score:

### Official Guide GMAT practice questions

### List of questions on this topic posted on Yin Tutoring:

- Three printing presses, R, S, and T, working together at their…-
- Source: OG2019 #118, OG2019 #113, OG2017 #96
- Difficulty: Sub-600 Level