Problem Solving

If 12x + 2y is 80% of 5y, what is the value of x/y ?

A) 1/6
B) 1/4
C) 2/5
D) 1/2
E) 5/8

Answer: A
Source: www.gmatprepnow.com
Difficulty level: 550-600

First translate the given information into an equation

12x + 2y = 0.80 * 5y

Then simplify this a bit.

12x + 2y = 4y
12x = 2y
6x = y

The question is asking for x/y. We now can substitute 6x for y to get x/6x. The x's cancel out to 1/6 or choice A.

Take care,
Sionainn

Brent@GMATPrepNow wrote:If 12x + 2y is 80% of 5y, what is the value of x/y ?

A) 1/6
B) 1/4
C) 2/5
D) 1/2
E) 5/8

Answer: A
Source: www.gmatprepnow.com
Difficulty level: 550-600

Sionainn's solution is perfect. It's the same approach I'd use.
However, here's another approach (for kicks!)

Let's try to find some values for x and y that satisfy the given information: 12x + 2y is 80% of 5y
Let's first let y = 20, and then figure out what value of x is needed.
We get: 12x + 2(20) is 80% of 5(20)
Simplify: 12x + 40 is 80% of 100
Evaluate: 12x + 40 = 80
So: 12x = 40
Solve: x = 40/12 = 10/3

So, x = 10/3 and y = 20 satisfies the given information.

What is the value of x/y ?
x/y = (10/3)/20
= (10/3)(1/20)
= 10/60
= 1/6

Answer: A

Brent@GMATPrepNow wrote:If 12x + 2y is 80% of 5y, what is the value of x/y ?

A) 1/6
B) 1/4
C) 2/5
D) 1/2
E) 5/8

We can create the equation:

12x + 2y = (4/5)(5y)

12x + 2y = 4y

12x = 2y

x/y = 1/6

Answer: A