After we subtract 411/811, we can rewrite quantity B as -1(59/124 -8/15)
Then, if we divide both quantities by (59/124 - 8/15) we get quantity A = 1 and Quantity B = -1
So, quantity A should be greater than B?

IMPORTANT: (59/124 - 8/15) is NEGATIVE
So, when you divide both quantities by (59/124 - 8/15), you are dividing both sides by a NEGATIVE value, which is not allowed.

There are a few ways to show that 8/15 is greater than 1/2

APPROACH #1 - number sense
7.5/15 = 1/2, so 8/15 must be greater than 1/2

APPROACH #2 - Use long division to convert each fraction to a decimal
1/2 = 0.5
8/15 = 0.53333.....
Since 0.53333 is greater than 0.5, we know that 8/15 is greater than 1/2.

APPROACH #2 - find common denominators
1/2 = 15/30
8/15 = 16/30
Since 16/30 is greater than 15/30, we know that 8/15 is greater than 1/2.

When dealing with 59/124 - 8/15, you were correct to rewrite each with the common denominator of 1860.
However, in doing so, you never changed the numerators (in order to create equivalent fractions).

Take: 59/124 - 8/15
Rewrite the fractions with common denominators: 885/1860 - 992/1860
Combine the fractions to get: (885 - 992)/1860
Simplify to get: -107/1860

After canceling obvious values, I converted everthing to decimals using a calculator. I only go 2 decimals places and round if necessary. Do you see any potential problems this way. I know the calculator is discouraged, but what are your thoughts? I ended up with the correct answer nevertheless

## Comment on

Fraction with Many Operations## I don't get it. When you

## Be careful. 59/124 - 8/15 is

Be careful. 59/124 - 8/15 is not equal to 8/15 - 59/124

If this were a sum, then it WOULD be true that 59/124 - 8/15 = 8/15 - 59/124

However, in the question we are dealing with subtraction.

Here's a different example: 5 - 1 does not equal 1 - 5

Does that help?

Cheers,

Brent

## do i have the calculator

## Yes, you will have access to

Yes, you will have access to an onscreen calculator on the test. It's pretty clunky though. Here's the video on how it works: https://www.greenlighttestprep.com/module/general-gre-info-and-strategie...

## after subtract 411/811, I

Then, if we divide both quantities by (59/124 - 8/15) we get quantity A = 1 and Quantity B = -1

So, quantity A should be greater than B?

## When you divide both

That's a great idea!

However, when you divide both quantities by (59/124 - 8/15), you are breaking a fundamental rule when it comes to the Matching Operations strategy (covered here: https://www.greenlighttestprep.com/module/gre-quantitative-comparison/vi...)

IMPORTANT: (59/124 - 8/15) is NEGATIVE

So, when you divide both quantities by (59/124 - 8/15), you are dividing both sides by a NEGATIVE value, which is not allowed.

Cheers,

Brent

## How is 8/15 greater than 1/2

## There are a few ways to show

There are a few ways to show that 8/15 is greater than 1/2

APPROACH #1 - number sense

7.5/15 = 1/2, so 8/15 must be greater than 1/2

APPROACH #2 - Use long division to convert each fraction to a decimal

1/2 = 0.5

8/15 = 0.53333.....

Since 0.53333 is greater than 0.5, we know that 8/15 is greater than 1/2.

APPROACH #2 - find common denominators

1/2 = 15/30

8/15 = 16/30

Since 16/30 is greater than 15/30, we know that 8/15 is greater than 1/2.

Cheers,

Brent

## I did not think to simplify

My first step was to cancel out the 411/811 from QA and QB. I was left with

QA: [(59/124)-(8/15)]/1/3 and QB: [(8/15)-(59/124)]/5/15.

From there, I got

QA: [(59-8)/1860]/1/3 and QB: [(8-59)/1860]/5/15.

From there, I got QA: (51/1860)/1/3 and QB: (-51/1860)/5/15.

Lastly, QA: 51/1860 x 3/1 = 153/1860 and QB: -51/1860 x 3/1 = -153/1860.

Answer: QA is greater, QB is negative. Where did I go wrong besides simplifying the 5/15 to 1/3?

## When dealing with 59/124 - 8

When dealing with 59/124 - 8/15, you were correct to rewrite each with the common denominator of 1860.

However, in doing so, you never changed the numerators (in order to create equivalent fractions).

Take: 59/124 - 8/15

Rewrite the fractions with common denominators: 885/1860 - 992/1860

Combine the fractions to get: (885 - 992)/1860

Simplify to get: -107/1860

You made the same error with all fractions.

Does that help?

Cheers,

Brent

For more on adding and subtracting fractions, watch: https://www.greenlighttestprep.com/module/gre-arithmetic/video/1069

## I thought you'd have to

## You COULD go that route, but

You COULD go that route, but it will take a while :-)

## After canceling obvious

## I think that's a totally

I think that's a totally legitimate solution, since it wouldn't take long to perform those calculations on the calculator.

## Add a comment