If you're experiencing a roadblock with one of the Manhattan Prep GRE math strategy guides, help is here!
p_gorsky
Course Students
 
Posts: 17
Joined: Sun Jun 02, 2013 10:34 am
 

Book 3: Geometry-Ch.6 pg. 121 Problem SWet #4

by p_gorsky Wed Sep 25, 2013 3:19 pm

There are 2 parallel lines with a transversal. x and y are supplementary angles. If x/x-y =2, what is x?

I don't understand the explanation or how we would set up that system of equations.

Thanks,
Pam
tommywallach
Manhattan Prep Staff
 
Posts: 1917
Joined: Thu Mar 31, 2011 11:18 am
 

Re: Book 3: Geometry-Ch.6 pg. 121 Problem SWet #4

by tommywallach Thu Sep 26, 2013 3:31 pm

Hey Pam,

Well, do you understand the relationship between x and y (i.e. x + y = 180)? This is because angle x has to be the same as the angle just above where the y is (because a transverse meets parallel lines at the same angle). And obviously, that angle (the one just above y) plus y has to equal 180, because it's a line.

From there, everything spools out pretty easily.

First, simplify the equation they gave you:

x/(x-y) = 2
x = 2x - 2y
2y = x

Then plug into the other equation:

x + y = 180

2y + y = 180
y = 60

so x = 120

Make more sense?

-t