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Non Zero Numbers

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Non Zero Numbers

by oquiella » Sat Oct 10, 2015 12:56 pm
If a, b, and c are non zero numbers and a+b=c, which of the following is equal to 1?

A. a-b/c
B. a-c/b
C. b-c/a
D. b-a/c
E. c-b/a


what is the quickest approach? plugging in numbers? Please explain.
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by GMATGuruNY » Sat Oct 10, 2015 1:00 pm
oquiella wrote:If a, b, and c are non zero numbers and a+b=c, which of the following is equal to 1?

A. (a-b)/c
B. (a-c)/b
C. (b-c)/a
D. (b-a)/c
E. (c-b)/a
Since the answers choices are phrased in terms of SUBTRACTION, rephrase the given equation in terms of subtraction:

a+b = c
a = c-b
1 = (c-b)/a.

The correct answer is E.
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by ceilidh.erickson » Tue Oct 13, 2015 3:15 pm
Picking numbers would work very easily here, too.

Let's say that:
a = 3
b = 5
c = 8

A. (3 - 5)/8 = -2/8 = -1/4 --> no

B. (3 - 8)/5 = -5/5 = -1 --> no

C. (5 - 8)/3 = -3/3 = -1 --> no

D. (5 - 3)/8 = 2/8 = 1/4 --> no

E. (8 - 5)/3 = 3/3 = 1 --> YES!

The answer is E.
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by Matt@VeritasPrep » Wed Oct 14, 2015 10:57 pm
You could also just monkey around with subtraction (since all the answers involve subtraction) to see what works.

For instance:

a + b = c
a = c - b
1 = (c - b)/a

It could also have been

a + b = c
b = c - a
1 = (c - a)/b

so either answer is fine.
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