How can greatest common factors and least common multiples help you work with fractions?

The greatest common factor (GCF) can help you reduce fractions. For example, 8/12 reduces to 2/3 because 8/12 = (2*4)/(3*4) = 2/3. Note the '4's in the numerator and denominator canceling. Also note that 4 is the GCF of 8 and 12.

The lowest common multiple (LCM) is used to get the lowest common denominator (LCD) which is needed to add or subtract fractions.

Example:

1/2 + 1/3 = 3/6 + 2/6 = (3+2)/6 = 5/6

The denominators 2 and 3 have an LCM of 2*3 = 6 (see note below), so the LCD is 6. Once all the denominators are the same, you add the numerators and place the result over the LCD.

Note: the multiplication trick only works if the GCF of the two denominators is 1. If the GCF is not 1, then you'll have to divide by the GCF.

hello,

as   long as they add up to 180 its correct.