Other questions like this?

[dux3000]

3x + 2y = 5

2x + 3y = 8

Quantity A: x

Quantity B: y

Solution: http://www.greenlighttestprep.com/module/gre-algebra-and-equation-solving/video/972

I solved this by solving for x and y, which turns out to be the slow way. The solution is a lot faster but I don't think I'd ever come up with it on the test. Does anyone have any similar questions that test the same concept so I can practice? 

[TakeruK]

The method the video used to solve this question is actually one of the standard ways you would solve a system of 2 equations with 2 unknowns. Especially when you notice the coefficients (numbers in front of) the x and y are similar in value, subtracting (or even adding) the two equations together to form another equation is a good idea. 

To find more practice questions, just google for systems of 2 equations and 2 unknowns and try the adding/subtracting the equations method on them. You might even find a worksheet that is designed for this method!

[dux3000]

Actually I did use the adding/subtracting method, but I changed the equations to 6x + 4y = 10 and 6x + 9y = 24 and then I subtracted them to get -5y = -14

 

I never thought about subtracting them before two of the terms were the same, 

 

[TakeruK]

Oh okay. Yeah, the key thing to remember is that since you don't need to know what x and y individually are, you just need to know which one is bigger, so you just need a relationship (i.e. an equation) that contains both of them  

[Brent@GreenlightGRE]

 Does anyone have any similar questions that test the same concept so I can practice? 

Here's a related question to try: http://www.greenlighttestprep.com/module/gre-algebra-and-equation-solving/video/973 

Cheers,

Brent - Greenlight Test Prep

[dux3000]

Here's a related question to try: http://www.greenlighttestprep.com/module/gre-algebra-and-equation-solving/video/973 

Cheers,

Brent - Greenlight Test Prep

Funny. I came across that same practice question a few minutes after I posted my question.  Thanks though!

[Brent@GreenlightGRE]

Funny. I came across that same practice question a few minutes after I posted my question.  Thanks though!

Yeah, in fact it's the practice question that comes immediately after the one you posted :-)