What is the sum of one third minus three sevenths?

Answer 1

To start of you can simplify the equation by making a common denominator, "1/3 - 3/7"

3 and 7 are your given denominators, so let's expand them to make the equation a little simpler, the lowest common number divisible by both our given denominators is 21, so lets multiply our numerators to match that

to make the first part of the equation fit into our common denominator we multiply the numerator by the same amount as the the denominator so

1 * 7 makes our numerator 7

3 * 7 makes our denominator 21

7/21

now we do the same to the second portion

3 * 3 makes the numerator 9

3 * 7 makes the denominator 21

9/21

now the equation can be much more simply seen as 7/21 - 9/21

so the answer is -2/21

or to answer the question numerically

21 goes into 2

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