What is the value of x? (1) 2x – 5y + 6 = 12

[ruben]

Hi,

I was wondering why the answer to this question is E. Even if we obtain the same equations when we isulate de x, we can still do:

2x - 5y + 6 = 12
2x - 5y = 12 - 6
2x - 5y = 6
2x = 6 + 5y
x = (6 + 5y)/2

Then solve for the y 8x - (4x + 10y) + 27 = 39 that equals to y=(12-4x)/2 .
Finally we can substitute x in the equation x = (6 + 5y)/2
=(6+5(12-4x)/2)/2 that gives us the x. Can anyone help?

Thanks :D


What is the value of x?

(1) 2x - 5y + 6 = 12

(2) 8x - (4x + 10y) + 27 = 39

When a data sufficiency question provides equations or algebraic expressions that can be simplified, make sure to do so before drawing any conclusions.

(1) INSUFFICIENT: After simplifying the equation, the value of x still cannot be determined without knowing the value of y:

2x - 5y + 6 = 12
2x - 5y = 12 - 6
2x - 5y = 6
2x = 6 + 5y
x = (6 + 5y)/2

(2) INSUFFICIENT: After simplifying the equation, the value of x still cannot be determined without knowing the value of y:

8x - (4x + 10y) + 27 = 39
8x - 4x - 10y = 39 - 27
4x - 10y = 12
2x - 5y = 6
2x = 6 + 5y
x = (6 + 5y)/2

(1) AND (2) INSUFFICIENT: Note that we ended up with the same equation from both statements. Therefore, we cannot solve for the value of x. On data sufficiency problems involving systems of equations, be aware of duplicates and always simplify the equations before making the final decision.

The correct answer is E.

[givemeanid]

Hi,

Then solve for the y 8x - (4x + 10y) + 27 = 39 that equals to y=(12-4x)/2 .

Umm no.

8x - (4x + 10y) + 27 = 39
4x-10y = 12
4x-12 = 10y
x = (10y+12)/4 = (5y + 6)/2 which is the same as first equation.

Careful while factoring!

[Guest]

Thanks!!!