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Fraction subtraction with changed denominator

Fraction subtraction missing value with a changed denominator

This math skill teaches how to find a missing fraction by subtracting a given fraction from it to reach a desired fraction. The skill involves making denominators identical to simplify the subtraction process and accurately compute the missing fraction.

Learn fraction subtraction with changed denominator

Teaching Transcript

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What number can we subtract 1 sixth from to get a difference of 2 thirds?

First, notice that our denominators are different. Any time we are working with adding, subtracting, or comparing fractions, we want our denominators to be the same. The lowest common multiple of 3 and 6 is 6

If we multiply top and bottom by 2, then 2 thirds becomes 4 sixths as an equivalent fraction

We can substitute that in, as they are identical in value.

Now that the denominators are the same, the only thing that matters is the numerator, and we can see that 5 sixths, minus 1 sixth, equals 4 sixths, or 2 thirds.