As Jess and Rich explain in this 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!
Read the full article: GMAT On Demand: How to Solve for the Value of an Expression (Without Solving for its Variables!)