How to subtract fractions

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SAT Math › How to subtract fractions

Questions 1 - 1

Which fraction has a value greater than that of X?

$x = \frac{4}{3}-\frac{7}{12}$

$\frac{7}{8}$

$\frac{3}{4}$

$\frac{2}{3}$

$\frac{5}{7}$

$\frac{3}{5}$

First, start by putting changing the fractions in the equation so that they have the same denominator.

$x=\frac{4}{3}-\frac{7}{12}$

$x=\frac{16}{12}-\frac{7}{12}$

Then, you can easily subtract the numerators. The denominator stays the same at this point:

$x=\frac{9}{12}$

At this point, you can reduce the fraction by dividing the numerator and the denominator by :

$x=\frac{3}{4}$

Then, to easily compare the fraction to the answer choices, you can change the fraction to a decimal:

$\frac{3}{4}=0.75$

By changing the answer choices to decimals as well, you can easily figure out which value is greater than :

$\frac{3}{5}=0.6<0.75$

$\frac{5}{7}=0.71<0.75$

$\frac{2}{3}=0.667<0.75$

$\frac{3}{4}=0.75=0.75$

$\frac{7}{8}=0.875>0.75$ , so $\frac{7}{8}$ is the correct answer.