IntroductionIn order to subtract fractions, we find the highest common factor of the denominator, and subtract one equivalent numerator from the other.
When subtracting fractions, we have to make sure the denominators are the same. So if we are given
in this case the denominators are the same, so we subtract 1 from 5
, which reduces to
When the denominators are different, we ‘make’ them the same by finding their least common multiple (LCM).
For example, in the problem , the LCM of 7 and 2 is 14So to make the denominator of 6/7 = x/14, we have to multiply the denominator by 2 (don’t forget to multiply the numerator by 2 as well!). We then get 6*2 / 7*2 = 12/14. Similarly for 1/2, we multiply the numerator and denominator by 7 to get 1*7 / 2*7 = 7/14. The equivalent fractions of 6/7 (12/14) and 1/2 (7/14) now have the same denominators, so we simply subtract 7 from 12 to get 5/14.