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Fractions: Adding and Subtracting
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Fractions: Adding and Subtracting

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Fractions: Adding and Subtracting

Adding and subtracting fractions involves finding a common denominator.

We can add or subtract fractions as long as they have the same denominator.

For example: 314+514=814 \dfrac{3}{14} + \dfrac{5}{14}=\dfrac{8}{14}

Find 28+48\dfrac{2}{8}+\dfrac{4}{8} and simplify

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What is 316+616\dfrac{3}{16} + \dfrac{6}{16}?

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Unfortunately, the denominators won't always be the same! 🤦‍♀️

If the denominators are different, then you must first make them the same by multiplying both numerator and denominator by the same number.

When the denominators are not the same, we need to find the LCM (lowest common multiple). Let's try 1227\dfrac{1}{2} - \dfrac{2}{7}

1

We can't subtract these just yet

Notice that the denominators are different.

2

What is the lowest common multiple of 2 and 7?

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3

14 is the lowest common multiple

We need to multiply both fractions to make their denominators 14. This means multiplying 12\dfrac{1}{2} by 77\dfrac{7}{7}, and 27\dfrac{2}{7} by 22\dfrac{2}{2}.

4

Multiply the fractions to make the denominators 14

12×77=714\dfrac{1}{2} \times \dfrac{7}{7} = \dfrac{7}{14} and 27×22=414\dfrac{2}{7} \times \dfrac{2}{2}=\dfrac{4}{14}

5

Subtract the fractions

714414=314\dfrac{7}{14}-\dfrac{4}{14}=\dfrac{3}{14}

6

Good work! 💪

The answer is 314\dfrac{3}{14}

What is 26+58\dfrac{2}{6} + \dfrac{5}{8}?

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