# The Knewton Blog

Our monthly newsletter features edtech and product updates, with a healthy dose of fun Knerd news.

## Video: How to Solve for the Value of an Expression (Without Solving for its Variables!)

Posted in Test Prep on March 23, 2011 by

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As Jess and Rich explain in this GMAT video, oftentimes on Data Sufficiency problems you’ll be given more variables than you have equations. This happens for two main reasons:

• You’re just given more variables than equations (you know, because it’s fun)
• You’re given as many variables as equations, but not all the equations are independent

In these cases, you won’t be able to solve for the value of every variable in the system. But — don’t be fooled! This doesn’t necessarily mean that E is the right answer. Sometimes, you may be able to solve for the value of an expression involving multiple variables — without actually knowing the value of those variables. Confused yet? Check out the video for a sample problem and a super helpful explanation!

Want more DS help? Check out more installments of this quantitative strategy lesson!