When adding or subtracting fractions, they should have the same denominator. In this exercise, we have two fractions with different denominators.

\frac{7}{1 2} - \frac{5}{8}

To find the smallest common denominator we should rewrite the denominators of both fractions using only prime numbers.

128 = 3 \cdot 2 \cdot 2 = 2 \cdot 2 \cdot 2

Now, in order to get a common denominator we need to multiply each fraction by factors that appear only in the denominator of the other fraction. Therefore, we should multiply

\frac{7}{1 2}

by

2

and

\frac{5}{8}

by

3 .

\frac{7}{1 2} - \frac{5}{8}

ExpandFrac

$\frac{a}{b} = \frac{a \cdot 2}{b \cdot 2}$

\frac{7 \cdot 2}{1 2 \cdot 2} - \frac{5}{8}

ExpandFrac

$\frac{a}{b} = \frac{a \cdot 3}{b \cdot 3}$

\frac{7 \cdot 2}{1 2 \cdot 2} - \frac{5 \cdot 3}{8 \cdot 3}

Multiply

\frac{1 4}{2 4} - \frac{1 5}{2 4}

Now that we have a common denominator, we can proceed to simplifying the expression.

\frac{1 4}{2 4} - \frac{1 5}{2 4}

SubFrac

Subtract fractions

\frac{1 4 - 1 5}{2 4}

AddTerms

Add terms

\frac{- 1}{2 4}

MoveNegNumToFrac

Put minus sign in front of fraction

- \frac{1}{2 4}

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