How to subtract fractions - GRE Quantitative Reasoning
Card 0 of 3
Solve for 
:
Solve for
Begin by isolating the 
factors:
Now, the common denominator of these two fractions is 
. Therefore, multiply 
by 
:
Now, you can subtract the left values:
Now, multiply both sides by 
:
Begin by isolating the
Now, the common denominator of these two fractions is
Now, you can subtract the left values:
Now, multiply both sides by
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Which of the following is true?
Quantity A: 
Quantity B: 
Which of the following is true?
Quantity A:
Quantity B:
First, consider each quantity separately.
Quantity A
These two fractions do not have a common factor. Their common denominator is 
. Thus, we multiply the fractions as follows to give them a common denominator:
This is the same as:
Quantity B
The common denominator of these two values is 
. Therefore, you multiply the fractions as follows to give them a common denominator:
This is the same as:
Since Quantity A is larger than 
and Quantity B is a positive fraction less than 
, we know that Quantity A is larger without even using a calculator.
First, consider each quantity separately.
Quantity A
These two fractions do not have a common factor. Their common denominator is
This is the same as:
Quantity B
The common denominator of these two values is
This is the same as:
Since Quantity A is larger than
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Simplify:
Simplify:
Just like adding fractions, when you subtract fractions, you need to find a common denominator. For 
and 
, the least common denominator is 
. In order to do your subtraction, you need to multiply appropriately to give your fractions this denominator:
Which is the same as...
Now, you can subtract the numerators and retain the denominator:
Just like adding fractions, when you subtract fractions, you need to find a common denominator. For
Which is the same as...
Now, you can subtract the numerators and retain the denominator:
Compare your answer with the correct one above