Brent@GMATPrepNow wrote:If 52x + 604 = 1400 and 151 + 13y = 350, what is the value of x - y?
A) -11/13
B) -11/52
C) 0
D) 11/52
E) 11/13
Answer:
C
Difficulty level: 550 - 600
Source:
www.gmatprepnow.com
The key here is to avoid solving the two equations for x and y.
We can do this by recognizing that each term in the equation
52x + 604 = 1400 is 4 times each term in the equation
151 + 13y = 350
For example, (4)(
151) =
604
And (4)(
13) =
52
And (4)(
350) =
1400
So, if we take
151 + 13y = 350 and multiply both sides by 4, we get the EQUIVALENT EQUATION:
604 + 52y = 1400
Rearrange to get:
52y + 604 = 1400
So, we have:
52x + 604 = 1400
52y + 604 = 1400
Since both equations are set equal to 1400, we can say:
52x + 604 =
52y + 604
Subtract 604 from both sides to get:
52x =
52y
Divide both sides by 52 to get:
x =
y
If x = y, then x - y = 0
Answer: C
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
