Basics

1. If the problem gives no specific variables, i.e., x, y etc., assume them yourself.

2. Relate such variables according to information given. At the very least, you should translate the problem into an equation or more.

3. Gather data given in each choice (1 and 2), and replace your existing variables with them to find out whether you can answer the question asked.

4. Though you’re not required to solve the equation, you sometimes need to do so in case it involves a quadratic equation which may give more than one unique answer. For example, x² = 4, giving x = 2 or -2. GMAT needs the one and the only one solution, and such mentioned answers don’t satisfy GMAT at all.